Of the three routes when I pull up Google Maps I'd use the middle one... if I had to go there. Lots of slow curvy and hilly two lane roads as I like curvy roads... even 68 which I would not recommend.
Where in Fla are you headed? A easier option would be the COE CG (Mckinney) on lake Allatoona north of Atlanta.
OR you could go on down to West Point lake at LaGrange as suggested above and this would put you through Atl mid day. If you want to avoid Atl and go to West Point lake it would change your route to west of Chattanooga and I-59 south to Gaosden and 431.
If you are headed to the west coast of Fla then Columbus, Albany, Perry/98 south would be my route.