Reddit mentions of Hiking Death Valley: A Guide to Its Natural Wonders and Mining Past

http://www.amazon.com/Hiking-Death-Valley-Natural-Wonders/dp/0965917800/ref=sr_1_4?ie=UTF8&qid=1322638315&sr=8-4

this book has a lot of good info on the trails and how to access them also.

Only the low part is flat. Mostly it's rocky. There are mountains on both sides of the valley that are spectacular. As for heat, yeah, it's hot in summer and it's hot on the valley floor most days because the air sinks down there and there's almost no wind there. However, if you get into one of the canyons it's pretty pleasant. I still wouldn't visit in the dead of summer but anytime from October - April is going to be rather manageable.

I was just there in March and it was warm but lovely. The thing is, that most of the foliage is sparse so you're not crushing delicate plants underfoot off trail. There are thousands and thousands of slot canyons and to walk into. You can get a guide and go exploring on your own, there are miles and miles of 4WD roads that lead to little used portions of the park, and there are endless walks to be had. Even if you're in established hiking areas there are side trails that many never bother with, here's a picture from Zabriskie Point you can walk anywhere amongst those formations (except where warned about mines) and just have a look around. Few people get off the beaten trail because they think it's not worth it or it'll be dangerous.

Once you're off the main areas all you need is a topo map, food, and ample water and you're pretty much set. It's real freedom in the park. On some of the little used portions, areas, you might not see anyone at all if you don't want to. The silence and desolation of the park is perfection. Unlike anything else, really.

Here's a book that has all of the non-mainstream hikes to do (plus the regular ones too). <-Not an affiliate link.

Scotty?

Johnson knew it was a scam and still was friends with Scotty, Johnson willfully built the castle because he fell in love with the area and the climate and lifestyle helped his health.

http://www.nps.gov/deva/learn/historyculture/death-valley-scotty.htm

Also, with the huge size of the park and the drastic geological differences that occur within the boundaries, there are many different elements present.

Here are some good books about the geology of the area/history and hiking.

http://www.amazon.com/Geology-Underfoot-Death-Valley-Owens/dp/0878423621

http://www.amazon.com/Hiking-Death-Valley-Natural-Wonders/dp/0965917800/ref=sr_1_1?s=books&ie=UTF8&qid=1427481871&sr=1-1&keywords=hiking+death+valley

http://www.amazon.com/Important-California-history-autobiography-detailing-ebook/dp/B00AQN23CY/ref=sr_1_1?s=books&ie=UTF8&qid=1427481886&sr=1-1&keywords=death+valley+in+49