Reddit mentions of Lodge Pre-Seasoned Cast Iron Reversible Grill/Griddle, 16.75 Inch x 9.5 Inch, Black

https://www.amazon.com/Lodge-Reversible-Griddle-Combo-Double-Sided/dp/B002CMLTXG

This is one of my favorite things in my kitchen.

TL;DR warning

Are you willing to invest in some tools? Do you like Five Guys? (skinny burgers) The fastest burger procedure that I know of is Kenji's Ultra-Smash technique, which makes a pair of thin patties in no time. Takes about a minute per burger (two patties with cheese). Details here:

http://www.seriouseats.com/2014/03/the-food-lab-maximize-flavor-by-ultra-smashin.html

You can also do a regular smash burger, which is thicker (McDonalds-thin), but takes longer (~1.5 minutes per side, about 3 minutes total per burger):

http://aht.seriouseats.com/archives/2012/09/the-burger-lab-smashed-burgers-vs-smashing-burgers.html

The advantage of the ultra-smash is that it's super quick & you can toss a piece of cheese to melt between two patties, so you can pump out a ton of burgers in no time. You will need a few tools, namely:

1. A metal cooking surface
   
2. A hi-temp heat source
   
3. A smashing tool
   
4. A high-quality spatula
   
5. A scraper (if doing ultra-smash)
   
6. A cheap IR temp gun
   
7. A cheap digital kitchen scale
   
   It's not rocket science, but getting a proper setup will let you have a workflow that makes cooking for a crowd a breeze. I have a big extended family, so I cook in bulk a lot, but I also use this for just my immediate family because it's so fast to get setup. There is an up-front investment required, but everything you'll buy will pretty much last forever, so it's worth it if you like to eat burgers!
   
   So the first two things you need are a metal cooking surface & a heat source that can pump out a lot of heat. I don't recommend a regular grill because they simply don't get hot enough; you need 600 to 700F to do this. You can either do a compact setup (a 2-burger surface with a single burner) or invest in a quality flat-top setup (more expensive, but lets you do more burgers at once). The ideal surface to do this on is a Baking Steel, which is very expensive. There are knockoffs for cheaper, but I like BS because they have a Griddle version with grooves to catch the grease:
   
   http://www.bakingsteel.com/
   
   You can also do it with cast iron. Lodge has a griddle for $25:
   
   http://www.amazon.com/Lodge-LDP3-Double-Reversible-Griddle/dp/B002CMLTXG
   
   If I'm just doing a single regular smash burger at a time, I use a 12" cast-iron pan. $28:
   
   http://www.amazon.com/Lodge-Cast-Iron-Skillet-L10SK3ASHH41B-12-Inch/dp/B00G2XGC88/
   
   If you do get into cast-iron, read up on this seasoning procedure (i.e. the way to keep it smooth & slippery without Teflon). It's a bit of a pain, but it's worth learning because anything you buy in cast-iron can be handed down to your kids because it lasts forever:
   
   http://sherylcanter.com/wordpress/2010/01/a-science-based-technique-for-seasoning-cast-iron/
   
   You will want a heavy smashing tool as well. I have this massive 2.5-pound cast-iron press. It fits inside the 12" pan above (but not the 10"). $13:
   
   http://www.amazon.com/Update-International-Heavy-Weight-Hamburger-Commercial/dp/B002LDDKZ6
   
   If you plan on doing ultra-smash burgers, you'll need a scraper. This is the one Kenji recommends, but you can probably find something locally: (Home Depot or Lowes)
   
   http://www.amazon.com/Plextool-Wall-Paper-Stripper/dp/B00AU6GQLQ/
   
   Anyway, getting back to the cooking part: you'll need a hi-temp burner. I like Bayou Burners, they sell them on Amazon. I have an SP10: ($50)
   
   http://www.amazon.com/Bayou-Classic-SP10-High-Pressure-Outdoor/dp/B000291GBQ
   
   I use that with my 12" cast-iron pan for when I'm just doing a few burgers for the family. 15 minutes = 5 burgers. You can also slap a flat surface like a cast-iron griddle or Baking Steel on that puppy. Also comes in a square version (not sure how the BTU's compare). I also have some KAB4 burners that I use with my Baking Steel, among other things. More expensive, but larger shell & burner: (more even heat over the cooking surface)
   
   http://www.amazon.com/Bayou-Classic-KAB4-Pressure-Cooker/dp/B0009JXYQY/
   
   For cooking more at a time, you can get a cooktop. Blackstone has a 36" cooktop available, but it doesn't get very hot (don't get me wrong, it's an awesome tool, but I've had trouble breaking 500F on mine, which means you're not cooking 1-minute burgers on it, plus the heating is kind of uneven, so you have to work in the hot spots for faster cook times). Also comes in a slightly smaller 28" version (but it's only like $50 less, so it makes more sense to get the full-sized version because you get so much more cooking area). The nice thing with this setup is that for $299 (or a bit less if you shop around at places like Cabela's), you can cook like 20 burgers at a time, it's absolutely insane! I make epic breakfasts on it. Plus it folds up for transport, which is really handy. We use it for all of our family events & holidays:
   
   http://www.amazon.com/gp/product/B00DYN0438
   
   A better version is from Tejas Smokers. They make camping stove carts that have burners built-in & have griddles available separately. They get super hot, downside is the cost: you can easily spend $700 on a nice setup.
   
   https://tejassmokers.com/Camp-Stove-Carts/23
   
   Oh yeah, Blackstone did just come out with a compact outdoor griddle which can run off those little one-pound green tanks if you want. They go for around $99 ($79 if you have an Ace Hardware near you). I have not tried this, but it gets good reviews. I'd be curious to see what kind of temperatures it can achieve:
   
   http://www.amazon.com/Blackstone-Portable-Griddle-Outdoors-Camping/dp/B0195MZHBK
   
   So that's a basic introduction to the cooktops: you need some kind of decently-sized metal surface, a hi-temp burner, a smashing tool, and optionally (but recommended) a scraper. You will also want to get a strong, high-quality spatula. A good one is $32:
   
   http://www.seriouseats.com/2010/07/equipment-the-due-buoi-wide-spatula-my-new-fa.html
   
   Available here:
   
   http://www.duebuoi.it/x/uk_usd/catalog/p/spatulas~805-16x10.html
   
   If you opt for cast-iron, get an infrared temperature gun (doesn't work too well on shiny metal surfaces like steel tho). $17:
   
   http://www.amazon.com/Etekcity-Lasergrip-1080-Non-contact-Thermometer/dp/B00DMI632G/
   
   A cheap digital kitchen scale is useful too, for measuring out the proper amount of meat. $14:
   
   http://www.amazon.com/Ozeri-Digital-Kitchen-Capacity-Stylish/dp/B003E7AZQA/
   
   This collection of tools ensures that you have the proper workflow: a metal surface to cook on, the ability to bring the surface to a high temperature (and know what that temperature is for precise control), the ability to weigh your meat so you can pre-measure out what you need, the ability to smash the burger down, and also to properly scrape it off. Again, it's not rocket science, but if you have a wussy grill or a crappy surface or weak smashing/scraping tools, you're gonna have a bad time. You just need the right setup to pump burgers out fast!
   
   So on to prep. For ultra-smash, you do a pair of 2-ounce ground beef balls. In the tutorial above, they use a mix of meat for 25% fat. I just grab some regular 80/20 ground plus some salt & pepper. For regular smash burgers, do a single 4-ounce ball (optionally 5 ounces...useful if you have a big cooktop for a bunch of burgers at one time & are only doing a single patty per burger). The nice thing is, there's no special prep required for the meat, so you can make all of your burger balls ahead of time. If you have 10 people & are doing ultra-smash, let's say half of them get 2 burgers, so 15 burgers total, or thirty 2oz balls. If you have 20 people & are doing regular smash, again with half getting an extra burger, that's 30 burgers total or thirty 4 or 5oz balls. So that takes care of prep...adjust as needed. If you're feeding mostly dudes, you'll want to add more seconds (and thirds) to the equation.
   
   There are a variety of buns you can get. Crap buns will make for a crap burger. See if you can find potato buns or brioche buns. Those are pretty soft. Buns aren't overly hard to make, but I have yet to find a decent recipe that takes under 40 minutes, so I usually only doing fancy home-baked buns for my family rather than a crowd. Buying 5 or 10 pounds of ground beef & making smash balls out of them will take you all of ten minutes, but making buns can take forever. Here's a good recipe if you want to try it out tho:
   
   http://smittenkitchen.com/blog/2009/07/light-brioche-burger-buns/
   
   Or this, if you wanna get crazy:
   
   http://www.seriouseats.com/2015/05/fresh-cemita-rolls-mexican-sandwich-burger-bun-bread-food-lab-recipe.html
   
   Or this one, nom nom nom:
   
   http://amazingribs.com/recipes/breads/brioche_hamburger_buns.html
   
   But eh, just hit up Sam's/Coscto/BJ's and buy some hamburger buns in bulk, problem solved. Or find a local bakery that has good rolls. There's a good shootout of buns here:
   
   http://aht.seriouseats.com/archives/2011/04/the-burger-lab-whats-the-best-bun-for-my-burger-taste-test.html
   
   (continued)

Try this first.
http://www.amazon.com/Lodge-Double-Reversible-Grill-Griddle/dp/B002CMLTXG/ref=sr_1_2?s=home-garden&ie=UTF8&qid=1341876329&sr=1-2&keywords=lodge+griddles

It's like a small, difficult to clean, more complicated version of a grill/griddle.

I was wondering if you'd chime in! I appreciate the info for sure. I'm thinking I'll either buy the 16"x9.5" Lodge rectangular dual griddle (I think I could close the lid with this one) or the 12"x12" Lodge griddle pan instead

Cheers! If you like the grill pan you may like one of those dual sided griddles (example below). It's great for large volumes or large items - it's what I use for grilled veggies (grill side) or whole fish (flat top). Just heat it to temp in the oven for even heat than transfer to stovetop for cooking.

https://www.amazon.com/Lodge-LDP3-Reversible-9-5-inch-16-75-inch/dp/B002CMLTXG

I would think the only advantage a griddle has over a skillet is when you have a really big griddle. That way you can use it for big family cookouts, both indoors and outdoors. Even so, I wasn't about to spend the money on this rectangular cast iron griddle until I found it on sale at TJ Maxx for $20. At that price, I feel I got a great bargain, because I can use it as a baking sheet as well as a grill.

I have this and I love it:

http://www.amazon.com/gp/product/B002CMLTXG/ref=oh_details_o09_s00_i00?ie=UTF8&psc=1

As others have mentioned, this thing is pretty much on my stove 24/7. Great for all breakfast foods, making paninis, and grilling meat. When I do steak (which I do on the flat side for optimal heat transfer), it'll get smokey enough to where I need to disable all the detectors in my house first. I'll let the thing heat up for about 10 minutes on high before putting the steak on. Of course, this is because I like my steak crusty on the outside while still rare to medium rare on the inside.

You might find a griddle that would suit you. https://www.amazon.com/gp/product/B002CMLTXG/ref=s9_acsd_simh_hd_bw_b3nYjEp_c_x_w?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=merchandised-search-3&pf_rd_r=WA7GTKXZD77RQ6W1NE3V&pf_rd_t=101&pf_rd_p=a739796d-be58-56b4-9c29-d4cc8a594442&pf_rd_i=3480716011

I can't find the one that I have because it's so old, but here is one that is similar cast iron griddle. It is reversible and the grill side comes in handle at times. Works great on a flat stove top.

These work great. The only thing I would suggest is that you get a two burner stovetop griddle. They're less than $50, are reversible (flat top option) and heat up very quickly. Possibly one of the most useful kitchen investments I've ever made.
Link

I'm thinking probably not. That style Wagner logo looks like the one that was made in China relatively recently. You could get a brand new Lodge reversible griddle for $45 or $30 on Amazon. You could probably find a vintage Wagner with the stylized logo (and Sidney -O-) on eBay for less than $50 too, though that would likely not be reversible. I'd keep hunting.

Ah, grill. I see your question now.

The quick alternative answer would be the same Coleman stove, but with a grill built in.

https://www.amazon.com/Coleman-Camp-Propane-Grill-Stove/dp/B000W4VD8C

I've used one of these for years and it's great. It does get nasty (greasy) under the grill - but its not terrible to clean. At $70 its a good deal.

​

Otherwise - you could get a cast iron grill thing to put on top of your existing grill. It's heavy and bulky, but it does the job well. I also have this for my Coleman 2-burner. It's not ideal because the heat isn't evenly spread - but once it gets up to temp it's not terrible.

https://www.amazon.com/Lodge-Reversible-Griddle-Combo-Double-Sided/dp/B002CMLTXG

You can't go wrong with lodge. My new stove top grill/griddle only set me back $25.

http://www.amazon.com/Lodge-Double-Reversible-Grill-Griddle/dp/B002CMLTXG

Amazon has them for ~$30, though I would recommend checking out your local kitchen supply stores. I see them for less very frequently.

I use a cast iron grill pan (here)on the shelf below my dutch oven to absorb the direct heat produced by my gas oven. Also, make sure your dutch oven is on the highest shelf possible/as far away from the heat source as possible. Both of these two tips helped the bottom crust on my loaves immensely.