Just did Nashville to SoCal
A few suggestions since I just rode from Nashville to San Diego about a month ago:
The Natchez Trace is a really nice road, but it can get a little boring. Also don't speed on it. The Speed limit is 50. I got a $100 "fine" from the Park Ranger. Talk to a couple of locals and they said the cops are pretty tough about the speed limit.
On you trip if you can make it to Flagstaff, AZ and then down to 89A to Sedona, it is really worth it. You can also do more of the Tonto National Forest on AZ, it is a great ride.
Also on your way up to Nashville is the Jack Daniels Distillery in Lynchberg, TN. It is a dry county, but the tour is cool and it is worth seeing.