We are driving from just outside of Milwaukee to Disney in October. The plan is to leave at 4 am to beat Chicago rush hour, stop in Cave City, KY at the Dinosaur World to let my little 3 year old dig for fossils and run for two hours and then drive to Perry, GA. There is a nice, cheap, Microtel in Perry that we like staying at. From Perry, it's just a 4-5 hour drive to Disney.
For our route back, we will probably leave around noon and stop south of Chattanooga for the night (haven't decided on the hotel yet). In the morning we are going to stop and enjoy Lookout mountain and do their incline train. I anticipate this to only take two hours. Then we are going to take IH 24 all the way to Paducah, KY and take IH 57 up to Chicago. IH 57 is a much more tranquil, there is less construction, and gas seems to be cheaper along that route compared to IH 65 (which takes you through Indy, Louie. and Nashville) IMO.
For your trip down, I would recommend taking I-57 through Illinois to I-24. Hopefully, this will allow you to follow the rain and not be directly in the storm the whole ride down. Best of Luck!