Very cool pictures. I love the drapery formation.
Probably an unpopular opinion but Marengo Cave looks more interesting than Mammoth Cave. Mammoth is cool and worth visiting but a lot of it is dry so not a lot of formations.
My favorite cave/cavern in the park system that I have visited is Carlsbad Cavern. Absolutely spectacular.
Unfortunately, the glaciers are melting away from Glacier NP. Over the last 150 years, the number of large glaciers has declined from 80 to 32. The number of smaller glaciers went from 144 to 49.