You might look into the roads between Cambellton, Palmetto, Newnan, Whitesburg, Roscoe, etc. This is due west of Atlanta and should be pretty easy to get to - people get there via bicycle. Usually very little traffic out there. No cops. You can take 154 south into Palmetto, then left on "Tommy Lee Cook" (just south of Palmetto) over to Jim Starr Rd then south on 70 into Newnan. This whole area is filled with quiet, pretty 2 lane country roads. Not a lot of places to stop, or eat or whatever except Nana's Country Kitchen in Palmetto.
Another area is...
http://www.quellet.com/bike_routes.htm
and click on "45 mile ride from the Budweiser Plant". But I don't know of a good way to get to Cartersville without getting on I-75 or going through a lot of stop and go crud.