National Corvette Museum, and Corvette Assembly Plant, both on Bowling Green, KY right off the interstate. Holley is also in BG, KY - could be an interesting tour if they have them.
After visting those "attractions", you'll owe it to your wife to stop in the Smoky Mountains, the Vanderbilt Mansion, etc.
Atlanta is your last good stop before Tampa, Bucktown or the Underground is where the action is. Nothing really else inbetween Atlanta and Tampa except truck stops and towns built around discount/factory-outlet shopping malls.
Plenty of Cracker Barrel's along the way too!