I agree with those who suggest staying along the coastal area and agree with their suggestions. Most of interior Georgia, the southern part in particular, is agricultural and a depressed (and depressing) region.

Once you have seen Savannah (recommended), and if you insist on getting off the beaten path, I have a couple of suggestions: If you can find them on a map, I would suggest a driving to Milledgeville and Madison. Madison (I-20 exit US 441), in particular, is an area that did not get torched by General Sherman in the Civil War and still has quite a few lovely old homes. It is certainly worth a drive through. You can continue up US 441 northwards through Athens (college town, home of the University of Georgia) and then hit I-85 to South/North Carolina. Alternatively, you can leave Madison vis I-20 and head directly east to re-join the coastal path.