there are direct flights from ATL to Minneapolis a couple of times a day. Minneapolis airport is a nice and easy airport to get around in... it is spread out, but not as hectic at Hartsfield-Jackson. My last trip to WI, I traveled through Minneapolis and was really pleased with the airport there. flight from Minneapolis to ATL was only about 2 1/2 hours so not bad at all.
you need to plan at least 3 days driving each way if going in MH. you will not average over 50 mph when you figure stops for fuel, etc. My DD lived in Wisconsin and the amount of time it would have taken to drive even without TT would have cut the time I wanted to spend visiting. for one person, if you search flights for good price, it is cheaper to fly than drive, when you figure fuel and overnight stops.
And for the naysayers, I much prefer traveling with my TT, but the reality of limited time for visit and restrictions on parking in DD's neighborhood, made flying the best choice at that time.