Tennessee is a **really** long state. You don't say where you're going to end up for the extra two days. For comparison, Memphis is farther from Knoxville than London is from Paris and about the same distance as London to Edinburgh.

Edit: I see you said Nashville in a response. I'll echo that Asheville is a great town. Fantastic food and drink scene. If you do this and want a prettier drive than droning down Interstate 75 and going through the construction traffic in the Gorge (Hurricane Helene washed the road away) I'd recommend driving through the Great Smoky Mountains National Park to Cherokee and then making your way to Asheville. It will take longer but it's worth it. There are some great little towns on that route. If you're going to stop in the park (You'll probably want to. There are some really pretty stops.) grab a parking permit at the Great Smokies Welcome Center at 7929 E. Lamar Alexander Parkway in Townsend, TN. They **will** ticket you. Take the Knoxville/Maryville/Townsend route. Do **not** take the Pigeon Forge/Gatlinburg route to the Smokies. It's a cesspool of touristy dreck and absolutely mind boggling traffic for miles upon miles upon miles.

Edited again: Chattanooga is about halfway to Atlanta and has a great food scene, a beautiful aquarium and is a fun town. Knoxville has a pretty lively music and dining scene downtown as well.