S/E Wyoming here. Been to all the above places a few times before moving to Wy, now we can't afford to visit there
Mt. Rushmore is way cool, so is Custer state park & the needles highway. If you only do 2 things in the area see these 2 attractions. We alsays camped in Custer, nice little town on the south of the blackhills.
Devils tower, drive by it, not worth stopping. Jim Gatchell (sp??) museum in Buffalo is excellent, well worth the stop. Nice KOA there also we camped at (all our camping was in a tent)
We always stayed at the KOA in Cody, lots to see & do there, it's a 3 or 4 day stay ifin you ask me. The Irma has a excellent prime rib buffet & lots of history. I assume you will be going to the museum in Cody, it's a 2 day visit.
Thermopolis has a really cool dionsaur museum & some wicked hot springs & pools. It's a overnight stay at least.
Jackson hole is yuppies paradise & extremly expensive but beautifull & worth the trip. We had aprox 1/4 inch of ice on the tent when tent camping in the KOA there in Aug, expect cold temps and be prepared for snow.
This is the best time to visit Yellowstone, it's shutting down from the summer & ramping up for the winter. The lodge right next to old faithfull is a must visit. You can spend a week in the park easy.