Cataloochee Valley, NC. It's beautiful. There's a nice campground with a decent bathroom. It's pretty small (20 something lots) and so not too many people. Me and a group of 10+ guys have taken an annual end of summer trip up there the last few years. And you can drive to it. Or if you want to rough it a little more I know there are a lot of backwoods campsites too. But the Valley as a whole is great. Historic sites scattered around. A lot of good hiking. And there's a nice sized creek that runs through it (and the campground), in which I have swam in multiple times. And not too many people around at all.

http://www.nps.gov/grsm/planyourvisit/cataloochee.htm