Accurately predicting peak fall color would make me a fortune! Still, I can tell you some variables to consider which will increase your chances of seeing great color. I can also tell you that not every season is an eye-popping year and can be comparatively dull.
There are four indicators essential for creating a great viewing season. You have to have substantial leaf volume, you need healthy leaves, leaves should have experienced optimal temperatures and precipitation over an exact time. Review my Predicting Fall Color and Autumn Leaf Display:
Also, check my webcam site, Best Fall Foliage and Autumn Color Web Cams. There are several Smoky Mountain and Blue Ridge cameras focused on the forests and trees. I know that this will not help when making reservations in August but it will show you leaf potential and current colors.
I am very familiar with the lower Blue Ridge Parkway and know that the end of October is an excellent time to visit. Early November can be good, too, if rains and winds don't increase the leaf drop. It is considered a good year when leaves stay on trees for several weeks.
Fog in higher altitudes on the Parkway can also effect views during certain times of the day. Fog can actually stop and reroute traffic.
Picture of a Fall View on the Natches Trace in Alabama - Photo by Steve Nix, Licensed to About.com