Just wanted to mention a couple of options since they seem pretty much within easy access to your itinerary.

Georgia has a neat little town called Helen a short ways north of Atlanta. This town is built with a strong German influence and would be a great place to spend a few hours.

Also in south Georgia, a trip on the Okenokee Swamp could be interesting.

Finally, when heading up from Dallas to Oklahoma, very close to Lawton is the Wichita Mountains Wildlife Refuge another great place to spend a few hours driving through.

All these places have camping, but you may need to check regarding the swamp what is and is not available.

See Big Al Carson in New Orleans for some really funny, funky blues.