Hills near White Sulphur Spring/Greenbrier WV

There are MOUNTAINS, not hills from Charlotte to the Greenbrier!

Unless you take a LARGE circuitous route, you will have to cross the mountains somewhere and I-81 and I-77 are used daily by other RVers and semi-trucks. Just get in the right hand lane and head up I-77 until you hit I-81, then to Rt 220 to I-64. These are good roads and you should have no trouble at all on them. Remember that just because the sign says the speed limit is 65, you don't have to go 65, especially up the mountains. Once you get to I-81, you will encounter less mountains until you are on I-64. Rt 220 is the only non-interstate driving and it is a 4-lane highway. There will be a few mountains when you get into WVA, but no huge mountains to climb, but there are mountains and some of the roads have curves in them to go around those mountains.

Just take is easy, don't get in a hurry and drive during the daytime if you are apprehensive.

There's nothing wrong with running I-81 to route 220 to I-64 but you could just take I-81 all the way to Lexington and get I-64 west there. This would make the route all interstate. Some of the pulls on I-81 going that way are long and steep enough that they have added a third lane for trucks on the way up. There are about 3 good hard pulls from Lexington to the Greenbrier. They are mountains but not like the Rockies. I'm guessing you're familiar with Fancy Gap on I-77, this would be the worst one you'll encounter.