Just returned from our trip. It was fantastic. I used a lot of advice from posts on here so thank you to all of you for helping make our trip so memorable. I'd post some pics on here but embarrassingly can't figure out how to.
For anyone planning a trip, I'd recommend not missing the Grand Tetons. I knew nothing about it (it's just south of Yellowstone Park), and it was absolutely breathtaking.
In the Badlands/Rushmore region, don't miss Custer State Park. That was one of the many highlights of our trip.