I've traveled around the Black Hills in South Dakota and Yellowstone Park in Montana several times. Here are a few suggestions: When in the Black Hills, stay a couple of nights in Deadwood, a fun little gambling town with an old west vibe. From there you can take day trips to any of the many attractions around the Black Hills (including Mount Rushmore). Then, in the evenings, if slot machines and blackjack aren't your thing, there are some great places to eat and usually some cool entertainment options, especially in the summer. On your way to Yellowstone, consider stopping at the Big Horn Battlefield, where Custer met his demise. It's really, really interesting! If you stop there you will be on track to enter the park via the Beartooth Highway (go through Red Lodge, MT), which Charles Kuralt called "the most beautiful roadway in America". It is spectacular -- you will not be disappointed. If you're short on time, you can see most of Yellowstone in 3 days and even have time for some of the shorter hikes, but plan for longer if you like back country hiking or if you absolutely must see every mud pot and geyser in the park. Make hotel reservations as soon as you can, or you will be staying outside the park. My favorites in the park are Old Faithful Inn at (you guessed it!) Old Faithful Geyser and the Lake Yellowstone Hotel, although I think any of the lodges and cabins would be just fine. If you have to stay outside the park, I highly recommend Chico Hot Springs, which is about a 1/2 hour drive from the North Entrance. Chico also requires far-in-advance reservations. Failing that, there are lots of lodging options at West Yellowstone just outside the West Entrance. I can't help much with the Jackson area. Happy trails!