Reddit mentions of Zion National Park (National Geographic Trails Illustrated Map (214))

I think the National Geographic trail maps are far better. They're also made out of a tougher material that seems like it would be water-resistant.

I've never rented an RV, mainly because of the cost. It seems to be more expensive than staying in hotels. The rental RVs you see most often are from Cruise America.

For Zion, there's 2 must see hikes. The first is Angel's landing. It's a relatively short hike (~5 miles) that will take 3-4 hours. The views are great, but the most impressive part is the trail, which is a true masterpiece in trail cutting. The second is the Narrows. The Narrows is often cited as the best hike in America, which I can not argue with. The Narrows is a thin canyon that is as wide as the river which you can hike ~16 miles up. You can do it as an in and out from the bottom or a through hike from the top. If you do it from the top you will need to get a shuttle and it takes ALL day. Ive done it both ways and from the top is the best way to go if you have the time and stamina. Ive rented equipment (which you will want the special shoes either way) and got a shuttle from Zion Outfitters. If you decide to do the through hike from the top you will need a backcountry permit. Try to reserve it ahead of time, but I did the last minute drawing without a problem. The East Rim and West Rim trails provide more typical hiking. I have not done the West Rim and it needs an overnight. The East Rim trail was great. We hitchhiked from the visitors center to the trail head without any problem (people are friendly in NPs) and then took a shuttle back to our car. National Geographic makes a great trail map if you want to see all the trails. In terms of lodging, there's two campgrounds in the park, lots of hotels in the town of Springdale right outside the park, a lodge in the middle of the park which always seems to be booked, and some BLM land a little to the south.

After Zion, Id go to Bryce Canyon for the morning (early) and do the Fairyland loop (~9 miles, mostly flatish) and check out some of the trails near sunset point. There's a shuttle so you don't need to hike back to your vehicle if you don't want. After a nice morning in Bryce, you'll want to drive east along route 12 (not how google takes you) towards Moab. Route 12 is straight out of a road runner cartoon. Along the way there's 3 places worth stopping that Ive found in order of awesomeness: Goblin Valley, Calf Creek Canyon, and Capital Reef. YOu may want to do the drive from Zion to Moab in 2 days depending on your schedule.

Once in Moab your choices for hiking are endless. Moab has lots of hotels, arches and canyonlands have campgrounds, and there's some awesome BLM sites along the Colorado river along route 128 just north of town. The 2 must hikes are Devil's garden loop in Arches and The Needles in Canyonlands. At some point you need to catch the view from Dead Horse Point or Island in the Sky but there's not much hiking there. If you have the time and resources, Id suggest doing some of the "adventure" activities from the outfitters in Moab. There's white water rafting, fan boat rides, canyoneering, and many other options. Ive always wanted to rent a 4 wheel drive high clearance vehicle and tour the Grand Staircase Escalante (which is being turned over to oil companies thanks to our dear leader).

In terms of timing, it seems like May 15th is a critical date. That is when the north rim of the grand canyon reopens after the winter. How does that line up with your schedule?

After you're done with Moab, you're about equidistant from Las Vegas, Denver, Albuquerque and Salt Lake City airports. If you're heading back to Vegas, Id go through Page AZ and hit The Wave (you need a permit) and north rim of the Grand Canyon. If you're heading to Albuquerque, Id spend a night at the Orvis Hot Springs and do a little hike in Ouray CO before heading to Chaco Culture. If you're heading to Denver, there's a million options along highway 70. If you're heading to SLC, it's mostly salt flats and indian reservations until you get close to Provo but there's lots to do near the metropolitian areas.

Hope that helps, let me know if you have any questions or want more details and please let me know how the trip goes!