JohnH--There are literally scores of streams on the N. C. side of the Smokies well worthy of note, but if you are limited on time those which flow into the north side of Fontana and their feeders are probably out of the loop. The same is true for Raven Fork and its feeders. That leaves those accessible, at least at some point, by vehicle and a relatively short walk. Think Noland Creek, Deep Creek, Luftee, Bradley Fork, Straight Fork, Beech Flats Prong, Kephart Prong, and the stream complex in Cataloochee Valley. Or, and this would probably be my top recommendation this time of year, Twentymile Creek. If you enjoy quite small streams, Indian Creek, an easily accessible feeder of deep Creek (half mile walk) is another fine option. It was the home water of the legendary Mark Cathey.
Beyond that, on a strictly mercenary note, buy my new book, Fly Fishing in the Great Smoky Mountains National Park: An Insider's Guide to a Pursuit of Passion
, and see what I have to say (there is a chapter on every stream). Enjoy your escape from the heat and humdity of dog days in South Carolina. Jim Casada