The kids were most excited about visiting Mt. Rushmore. We've been working on memorizing the US presidents in school and they were excited to visit this historic monument.
I visited as a kid, but I don't remember being able to walk down and around the monument. I loved getting to see the carvings from various angles, as well as see a model of what Mt. Rushmore was originally supposed to look like.
My favorite two parts of our visit:
1) Listening to Bethany (age 3), point to her postcard and ask everyone, "What your favorite kid? I like Winc-on!"
2) Watching my kids interact. Not sure what happened, but they seemed to all break into partners and they were so sweet with each other. Lots of holding hands and being buddies. It wasn't planned...and those are the best moments!