Zion is my favorite national park so far. At least it's the most spiritual place for me. Didn't make it all the way up Angel's Landing, but damnit I will someday!
The Grand Canyon is amazing and I'd love to do a river float trip through it someday.
Bryce canyon is beautiful and on a trip out west with my I laws in 2008 we hiked a lot of random slot canyons in the area around Zion.
I'd like to get to every US park during my life.
Mesa Verde was fascinating albeit harrowing for someone afraid of heights.