Take the 4Runner and spend an afternoon doing the BLM non-maintained road from Goodsprings to the backside of Mount Potosi. Some really spectacular rocks and scenes (vistas, open deserts, mountains). Just about 1 1/2 hours of driving if you go straight through, but there are plenty of side trips trails. It won't ruin your truck either, although you'll have a couple of 'oh crap, why am I driving here' moments. I've even done it in a mini-van, but I wouldn't recommend that.
As for driving in Vegas, no different than any other city, better than LA, St. Louis, or Detroit.