The Dragon is a great road, I've done it several times. It's very tight with no long straights so 35mph is fast on it. Be very careful not to go across center, there may be someone coming the other direction and most all the corners are blind. Ride it during the week if you can. It's packed with sport bike riders (squids) on the weekend.
Another road in the same area I actually like better is the Cherohala Skyway. It's a new (5-6 years old) road at a high elevation in the mountains between Robbinsville, NC and Tellico Plains, TN. You have to have a pretty new map to see it. You can ride it faster than the Dragon, all the curves are long sweepers and there is not much traffic. It's about 50 miles long.
I had never been on US421 between Bristol, TN and Boone, NC until a few weeks ago. It's the best kept secret in great roads. There are two mountain ranges you go over and both are a lot like the Dragon. There is a little town called Shady Valey in between the mountains with a country store that caters to the bikers. Not much traffic and very senic roads in all directions. Take highway 133 north from Shadey Valley to see the "World's Shortest Tunnel".