I think caves have a bit more variability to them which makes them a bit more thrilling. Mines, being artificial, are fairly uniform and while very cool don't have the variability or the natural aesthetic that the most impressive caves do.
The ocean is a key point for sure. Go south inColorado and you have the sand dunes and the indigenous housing carved into the rock walls, go east and you have the prairies and grasslands, go halfway west and there is the Rocky Mountains, go further west and it’s landscape mimics that of the desert with the high erosion canyons. Also, can’t sleep on Red Rocks amphitheater and Denver’s culinary options. We also have 54 mountains that are above 14,000 feet that provide views that CGI can’t even match.