Reiterate some that have been mentioned later in the thread.
1) Little Big Horn National Battlefield - It was quite interesting. It's name was changed from Custer some years ago.
2) Craters of the Moon National Monument - It's near Arco, Idaho. Really enjoyed my visit there. A good day will cover it in fine detail. Liked the other worldly rock formations found here.
3) Capital Reef National Park - Another interesting park. Another park that features lots of rock formations, but totally different from the rock formations at Craters of the Moon. Plus there are other features to view while there.
4) Saguaro National Park - Another different, but very interesting national park. Being a desert national park, it's totally different from one of the national parks in the Rockies.
5) Mesa Verde National Park - Down in the 4 corners region of Colorado, I mention this one because I don't hear it bandied around a lot. Again, a different national park due to it centering on the Ancestral Puebloan culture, and their cliff dwellings.
All but Saguaro were visited by us this year. Saguaro was visited in 2014.
