We were there last year in August and it was pretty crowded, but we didn't have any problem with the shuttles. We had quite a bit of rain also. Transplant is right that you can cut off a lot of the distance to Devil's Bridge with that route. We did the Chuckwagon area and it was about 80 minutes there if I remember right and 45 minutes waiting in line to get the photo. Everyone was real nice and would get your pictures for you, but the earlier you get there the better. Be careful about that last scramble before you get there, I'm still surprised at some of the people that made it past that.
All Trails is a must to plan out distance and elevation changes. I did make it around in my usual walking shoes and some old golf shoes that I wear that are as good as some hiking boots for stability in the sole. But do protect your feet. A sneaky little trail just south of the main part of town is Raven Cave, short and really neat small cave formation in the side of the cliff above the river.
One thing we did that wasn't mentioned here was go south to Montezuma's Castle and Well (two separate sites). Completely void of people for the most part.
A dream retirement job would be driving a shuttle bus there and then going to enjoy the scenery, but they need a couple more golf options.
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