I’ve been to:
Arches – UT
Badlands – SD
Bryce Canyon – UT
Capitol Reef – UT
Grand Canyon – AZ
Grand Teton – WY
Great Sand Dunes – CO
Great Smokey Mountains – TN,NC
Haleakala – HI
Mammoth Cave – KY
Mesa Verde – CO
Rocky Mountain – CO
Yellowstone – WY
Zion – UT
(and plan on visiting Black Canyon of the Gunnison this summer)