I had exactly the opposite reaction. It was much, MUCH smaller than I had imagined.
I stopped at the Painted Hills in North Dakota (Roosevelt Park) and there was literally a herd of buffalo wandering through the parking area. They clearly didn’t give a damn about us or our vehicles, it was neat. 
The summer of my 13th birthday I had Floyd tickets. Days before the concert my great great aunt (yes, 2 ‘greats’) decides to kick off at age 93. For some god forsaken reason, even though my dad worked for an airline and we could fly for free, my parents decided to drive us halfway across the country to Nebraska for the funeral. After the whole ordeal was over - including our van breaking down, lots of yelling, terrible food at the memorial service - and I missed the concert that I was looking forward to more than anything else that year, my parents asked me, “do you want to go straight home so you can be with your friends on your birthday, or do you want to drive up to South Dakota to see Mt. Rushmore? It’s your birthday so you get to choose.”
“I want to go home to be with my friends.”
We went to Mt. Rushmore. And I still haven’t seen Pink Floyd.
FUCK Mount Rushmore. Pile of shit.
Surprised no one yet has mentioned my favorite site in the area! Might be cooler if you were a child of the Cold War. Guaranteed delivery 30 minutes or less. Gotta love it!
Yeah, Mount Rushmore only takes a couple of hours. A pleasant walk. For some reason it gave me a nice feeling of patriotism. It is one of of “national shrines”, if you will. I found the passage with all of the state flags neat. And given the prominent place it has played in our popular culture, I was glad to go.
My family and I differed on the Badlands. We stayed in a cabin in the park. I wanted to stay for several days, walking through all of that wonderful desolation. My family was underwhelmed and we cut our stay there 1 day shorter and spent an extra day in Custer State Park.
It is one of those things that can only be appreciated in person, like the Grand Canyon (which is amazing in pictures but fall WAY short of what it is really like) or Niagra Falls. The problem with Mount Rushmore is that it is impressive - for a few seconds - and then you are done. It’s like going to the Four Corners, you go there, stand on the spot, ponder the enorminty of standing in four states at one time and then start wondering what the rest of your day will be about becuase that took all of 15 seconds.
We were wondering if there is an element of culture to being really awe-struck by Mount Rushmore. From our Canadian perspective, it was cool, yeah, but didn’t inspire any emotions in us at all. Crazy Horse was by far the highlight of that day for us. Is there a more visceral reaction to Mount Rushmore that we would (naturally) be missing that Americans have in seeing it?