The stretch from statesboro to Athens allows for more side of the road camping, then say, in a random field - the trek shouldn't take longer than three days, tops. As a point of reference, it wasn't until i got to the coast that I started staying in actually campsites, or "legal" places. There's really not much between statesboro and Athens (the rolling hills of south-east GA), so with that, you'll have more than enough places to pull off to and set up a tent.
I agree about the more direct route, though in terms of landscape, etc, you're going to see a lot more elevation changes (especially coming into north GA); while it's loop, as you say, the ride down the coast is really super nice (south carolina is an experience in and of itself - the people are awesome though; and the Virginia/N Carolina coast (outer banks) is nice as well)
Too, the maps for the Atlanta route are good (some spots need some updating) so if you did the coast line to Statesboro, you'll at least have a true set of cycling maps to fall back on.