Yesterday I showed some photos from the hike to this arch. Cassidy Arch is one of the most popular hikes in Capital Reef NP. If you look close on the left side there is a man rappelling. He gives a perspective on the size of this arch.
I have been in 4 of the Big 5 out there, over two different trips, and I would go again in ten minutes if I could. Love that you got an example of the scale because it is simply difficult to get across to someone who has never been there.