I am planning a 4 week road trip across the US with my fiancee and our two dogs. We will be leaving in late September from California and going across to Maryland and back. We have planned the first portion of the trip up to portland, OR, then over to Yellowstone and making a stop in Sioux Falls, SD. From there Minnesota, Wisconsin, Illinois, all across highway 80/90, through to MD. I so far have no stops planned in any of those areas east of South Dakota....any suggestions?