I'm gonna cheat here and say The Cabot Trail on Cape Breton Island is by far the most fantastic driver's road I have ever experienced. Gorgeous scenery and a sinewy track along a craggy coastline. Hairpins, esses, dramatic elevation changes and sweeping vistas of the North Atlantic all make for a memorable adventure behind the wheel. There's an example in the attachement below. Of course, its about 15 hours from my home, but whatever. Its still an experience you should have once in your life.
Somewhat more locally, Route 100 in Vermont is generally recognized as one of the top 10 routes in America.