回复：From Yellowstone to Mt.Rushmor

I did not remember any sizable town that provide any good option for either motel or restraunts between two point.

Leave before noon from Yellowstone and you can make it to Rapid city a little bit late in the same day. Drive from Park to HW90 takes longer time than you expected.

However, if you have to stop, I think it should be Cody, not far from Yellowstone meaning you can still whole day in the park.