There's not a huge amount of vehicle access to the Smokies: there is one main road that crosses the park (US441). It's very popular in leaf season, though I expect you'll be there after the peak tourist time (and driving up on weekdays will help.) That road hits Newfound Gap, with a large parking area and access to the Appalachian Trail. A side road, if it's open, goes to Clingman's Dome, which is worth a visit just for the view from the tower. There are turnouts on 441 with overlooks that might provide decent photos, depending on the time of day.
Cades Cove is one of the best spots in the Smokies for photography. There is a loop road, with plenty of places to stop for photos, plus some original settlements. Cataloochee is an interesting place to visit, too, though it's somewhat hard to drive there from the rest of the park. There is a "pioneer farmstead" at the Oconaluftee visitor center on the NC side of the park, which may offer some nice images in good light.
Fall color begins at the peaks (over 6000 feet) fairly early, then marches down into the valleys. I've made some nice images even in early November with full fall color in the lower valleys, looking down from the higher overlooks. It really depends on the year, though. The attached image is from a November hike, shot on 11/12/08 with a crappy p+s camera (not a photo trip....), just to give you an idea of what it might look like.
