Straight Fork, etc.
Straight Fork's a great recommendation. I'm also a big fan of Bradley Fork starting in Smokemont CG. Deep Creek is nice too.
One thing to think about though, is that by the time you've driven there from Townsend, you've passed an awful lot of excellent water and spent a decent amount of fishing time doing it. That's not to say it's not worth doing, as that's an amazing drive. You soak up a lot of great scenery, and there's nothing that says you MUST resist the urge to get out of the car and wet a line in some unplanned location...just that you may never get where you're going. Personally, that's my quandry when fishing the park. What an awesome problem to have!
Clearly, there's enough awesome water on the NC side to make a trip of it, using Smokemont (and others) as a jumping off point. Just something else to consider.