We just finished a several weeks road trip that is similar:
- Started in Rapid City (Badlands, Rushmore, Custer SP, etc)
- Deadwood
- Headed to Devil's Tower
- Up to Theodore Roosevelt in ND
- Into Montana (Little Bighorn, some state parks) to Billings
- Took Beartooth into YS (recommend Lake Hotel over the other areas)
- Down into Tetons (recommend Jackson Lake Lodge)
- Into Idaho (City of Rocks, Craters of the Moon)
- Down into Northern Utah (Golden Spike and tons of hiking)
HIGHLY recommend doing this. Wanted to add in Glacier but it was just too much driving.