seems to me that the way I would go would be dayton to davenport, to omaha, to sioux falls, to rapid city,to billings and drop down into yellowstone from the North. roughly 2000 miles/4 days just to get there.
avoid wall drugs, check out the corn palace.bad lands natl park. see rushmore and crazy horse memorial. devil's tower. you will have over a week of driving and a week to sight see. at yellowstone make a one day trip on the N loop and one day on S loop and try to hit old faithful right.
much to see, little time to see it.
bumpy
