Yellowstone questions

We went in mid-September and it was more crowded than we thought, so I cannot image what a zoo it would be in mid-summer. We also had snow one of the nights, but the days were very pleasant, so fall is a good time to go.

I would definitely say to see the Black Hills, and suggest staying at Custer State Park. They have the fall Buffalo roundup, which will tend to make things more crowded. If you don't want to see that, schedule your Custer stay either before or after roundup week.