I've been lurking on this board for awhile and got some good tips and wanted to thank everyone. We just got back from a trip to the South and enjoyed the following (we only wanted casual - no upscale places that required dressing up!):
Charleston: Jestine's Kitchen, Pooghan's Porch, Somewhere North of Broadway, Hominy Grill
Savannah: Lady and Sons, Mrs. Wilkes Boarding House (made it there 5 minutes before closing and they were extremely gracious to us).
Nashville: Jack's BBQ.