This may sound weird, but the Okefenokee National Wildlife Refuge in southern Georgia is absolutely amazing. Specifically, stay at Stephen C Foster State Park and base your activities from there. They offer boat rentals or take your own kayak to explore the swamp, the fishing is great, and you are literally in the middle of nowhere. It's so far out in the sticks that the rangers have to live there on a rotating basis. After a few days there head over to Hilton Head or Savannah..... Or on the way to the Swamp stop for a day or two at Stone Mountain, explore that and all that Atlanta has to offer before heading on south.