Your Mapquest is WAY off. We are 30 minutes southwest of K-zoo and 21 1/2 hours is the longest it ever took us...and that is going a longer way, getting stuck in horrible construction, and numerous food/bathroom breaks. For you, I would say no more than 18 1/2-19 hours, plus stops.
We will take 131 south to Indiana Border, 13 South to Indianapolis (never done this portion, we normally take 94 over to 69 South), 65 South thru Nashville, thru Atlanta and hook on to 75 at Macon Georgia. Mapquest is saying 21 hr 25 min from Kalamazoo MI.
This is only our 2nd time driving. We are hoping to drive straight thru.
Weird question, but....how do your kids sleep in the car, seatbelted? Our kids have never been much into sleeping in the car and I wonder how they will actually do sleeping sitting up with a seatbelt on???? Obviously they will have a blanket and pillow, but any other ideas?