Well, since you mentioned it...
In NC
Old NC 105
Uwharrie (we're going later this year, look for it on Rally Points)
Tellico
The Outer Banks
The Barrier Islands
If you're near the coast, the Catfish Lake / Black Swamp / Great Lake area was pretty good wheeling before the fire, kinda got some of it blocked off now.
gaiagps.com has some reasonably detailed maps with dirt, gravel, and harsh roads (as well as non-vehicular trails) on them. Thing about NC is that most of the good wheeling is "unofficial", as in, offshoots from forest service roads, and abandoned logging roads. You gotta know how to look for them. Some of them get pretty covered over by the forest, particularly during the summer.
Avoid private property like the plague. See any sign or gate, turn around immediately.
DO NOT go faster than about 35 mph on any dirt road in NC. Washouts move with every rain, and there is usually other traffic everywhere I've ever been.
Beware of hunters in hunting seasons. They're a friendly lot, respect their activity and they'll respect yours.
Can't speak for SC, don't know that I've ever been there actually.