As an all around "go to" I'd pick a tapered, knotless 9' 5x. I like Rio leaders a lot. A lot of trout books are written for quiet water wereas in the Smokies you'll be wading upstream in riffle or pocket water quite a bit and a small, dark fly can be hard to see in foamy, turbulent water. A #12 Thunderhead or any of the parachutte types with a tuft of white calf hair (or possum) will work. A tan elk hair caddis works great- floats like a cork and easy to see.
In the riffle/pocket areas- try to pick out the main channel and then look for a small chute or slick- about bathtub wide and a couple of bathtubs long and cast to the top of the seam- generally a good place.
BTW- a lot of folks think "possun" is sort of the "hillbilly" alternative to calf hair- not necessarily so; Englishman Frederic Halford- father of the dry fly- was listing it back around 1900 "ish".