Go early, before it gets nasty hot in South Dakota and super crowded in Yellowstone.
All the entrances to Yellowstone are easy except US 212, Beartooth Highway. If you look at a map it's obvious why that's a problem. Only a crazy person would tow a TT across Beartooth Pass.
The entrances from Gardiner, Cody, and Jackson are easy drives.
Don't waste your time at Wall Drug. It's a glorified junk store. Do take time to visit the Minuteman Missile site nearby.
Stay inside the park at Yellowstone if possible. You will spend a lot of time driving, but staying outside the park will make it worse.
