I'd do 65/231 as well if you are on the west side of Florida.
If you need to do Atlanta, you want to roll through in the middle of the workday if you can. Traffic there is just never good and when it goes bad it is atrocious.
My two cents is that Nashville is a long day on the road if you start out going through Chicago. Paducah, KY would be a much better first day's destination if you can swing that. That would make it possible to get through Atlanta on your second day if you wanted to put in 7 or so hours on the road.
I'm a pessimist according to my wife, realist according to me, but first days on the road never cover as many miles as you plan for without pain and suffering.