For the past few months I've been planning a road trip from NJ to Memphis and down the "Blues Highway" (Highway 61) down into Mississippi. Hopefully I'll have time to actually take the trip this year. I picked up the following books you might find useful for your trip:
http://www.amazon.com/000-Places-U-S-Canada-Before/dp/B001RTS8ZM/ref=sr_1_3?ie=UTF8&s=books&qid=1270192044&sr=1-3
http://www.amazon.com/Southern-Belly-Ultimate-Lovers-Companion/dp/1565125479/ref=sr_1_1?ie=UTF8&s=books&qid=1270192291&sr=1-1
http://www.amazon.com/Road-Trip-USA-Cross-Country-Adventures/dp/1598801015/ref=sr_1_1?ie=UTF8&s=books&qid=1270192324&sr=1-1
The first book has been particularly helpful. Everyone has their own ideas about what they find interesting or exciting; for me it's historic sites, fun roads, and authentic local cuisine. This book points you to those don't miss places and gives you enough info to determine whether you'll really enjoy them.
For fun roads check out
http://www.motorcycleroads.us/
After doing some research I think you'll wish you had a lot more than 3-5 days for your trip. A least you'll be able to make the most of the time you have. Most important, don't forget to stop for an authentic cheese steak at Pat's or Gino's in South Philly, and while you're at it make an appointment for a triple bypass down in Alabama.
