CAA will route you around the Summersville area route 19 and take you into Charleston. You don't have to take that detour, it will add lots of miles and time to your trip. There are alot of hotels on 19 in the Summersville area, this is where we stop when we drive. I have heard many warnings about speeding enforcement in this area (picking out Ontario plates) so we always do ONLY the speed limit as it does drop in a few areas but still alot faster then going through Charleston. However, we have never seen a cop in this area we still heed the warnings.
Just stick to the speed limit and you will be fine.
I have driven the I75 route but would only do this in the winter, it is a long boring, straight drive. The 79/77/95 route is very nice in through the mountains.
Kim