I know of several areas that you might like.
One place that have stopped at on several occasions and always wanted to camp at but didn't is if you take blue diamond out towards Pahrump. When you pass Charleston (the way to Red Rock) you go roughly 2.3 miles and you will see a...rest stop/pit toilet building on the left (south side of the road.) This road will take you out to GoodSprings. Along the way though, there are several great look outs of Vegas. A word of caution though, I have had a late night run in out here with a shady character(s) that were spot lighting. Great trail for geocaches though.
http://maps.google.com/maps?f=d&source= ... =UTF8&z=13Another spot that you might be interested in is Gold Butte. It will take about 4-5 hours to get to the end of the road(paved) but then you will have a good day or two of just gravel everywhere. Old mines, a few geocaches and some great desert views. Good place to go for a few days to get away. Make sure you take extra gas. 1 extra 5 gal would be fine unless you really hit the trails and then you ant at least 2 5gals.
http://maps.google.com/maps?f=d&source= ... =UTF8&z=12FYI, this is just to the trail head.
Another Spot is Mormon Mesa, it is out by Mesquite, some nice trails there, nothing like the Hump and Bump but expedition trails. Nice camping areas, old deserted buildings, geocaches and far enough away to be nice but close enough to where you don't really need extra gas.
http://maps.google.com/maps?f=d&source= ... =UTF8&z=12Just thinking another spot I hit about a year ago was the Shoshone area. It is just on the other side of Pahrump in Cali. Hit several pretty nice trails in there. Didn't get to do nearly as much as I wanted to my transmission decided to act up while out there so I limped back home to get some work done.
If looking for smaller trail runs, there are a ton up on Mount Charleston off Kyle Canyon Road...or Wheelers Pass which goes from Indian Springs to Pahrump, over the mountain. There is Bitter Springs out by Valley of Fire. I always liked Jitterbug trail but the BLM shut that one down, great spot for yotes, mines and old mining home sites.
Hope that helps.