400 miles isn't that far. It's approximately the distance from Minneapolis, MN to Milwaukee, WI, which is a trip that I've done nonstop. It takes around 5.5 hours, which isn't too bad. Start around noon and arrive just a little before dinner.

Minneapolis to Chicago is a bit longer (a little over 400 miles), and takes about 6 hours. For that I'd probably need to stop somewhere to eat.