Pretty much every stream in the Smokies has wild bows, and brookies if you get up high enough.
I fished Roaring Fork, Little River (above Elkmont CG and in the town of Townsend, the former was much more enjoyable), Middle Prong, Cosby Creek, and a small stream near Greenbrier. I did well in all of them, Cosby (above the CG) was probably the best of them, mix of brookies and bows. If I had to do it over, I'd probably add a real high elevation stream, like Road Prong.
I agree on staying away from Cade's Cove and Abrams Creek from a fishing perspective. Crowded and not as pretty as the "deep woods" to me. It probably is the best overall fishery in the park. But it's a slowish limestoner. You got plenty of that kind of fishing here in PA. The high mountain streams are quite a bit different than the mountain freestoners in PA, so hitting them is getting a bit of a different experience. You'll probably catch more there too.
The tailwaters, like the Holston, may be very good but that kinda fishing just doesn't appeal to me as much as getting up in the mountains and the deep woods. When I'm in the Smokies, I want the mountain stream experience, you know?
I would think October is a very good time to fish there.