I think the fear of Atlanta is overrated (assuming you don't try to go thru at rush hour).
I agreed with this until we went thru ATL in September. Got there around 1 PM on a Friday and it was a sold traffic stop and go on I-75 from the I-20 intersection north of town all the way to 25 miles south of town. Took several hours. They have really interfered with the traffic flow by removing traffic lanes and giving them to that express route. Take that if you go thru.
We have taken to going thru Alabama from the Mobile area lately, end up on I-55 I believe. And then I-10 to I-75.
Chattanooga has become a big Pain in the rear lately too with a lot of construction.
Best bet is to plan your trrip to hit ATL on Sunday.