I'd do the coast up and the mountain route back.
Cool towns?
Stay in Aiken, SC for the night at the Willcox downtown. Great, very cosmopolitan place with excellent restaurants.
Eat at the track kitchen for breakfast. It is on a dirt road in the center of the race horse stables and track.
Charleston for lunch. Stay the night in Pawley's Island.
Head north to Atlantic City or New Bern, NC. Neat places.
I'd drive the Chesapeake Bay Bridge then explore Easton or Cambridge, MD. Head over to Annapolis for the night. Stay downtown.
From there I run out of recommendations...
On the way back, Lexington, VA is a great town. Tour VMI. Asheville, Brevard and other small towns are great in NC.
Helen, GA is neat but there are any number of cool town throughout the Smokies.
Huntsville, Ala is a a great place. Check out the space center there. Can't miss it, there is a Saturn 5 parked out front
Enjoy!