Another question…I have read that a lot of people rent the Canyoneer boots at Zion Adventures. Is this necessary for a July hike? Can't decide between renting, keen sandals, or maybe just old tennis shoes.
go with light weight trail runners. keens get a lot of sand in them
Definitely some old light-weight tennis shoes. No need to rent the Canyoneer boots. I did the narrows in an old pair of ultralight New-Balance training shoes and had no problems at all! Keen sandals would also work but you may get a bit more sediment stuck in your shoes.
We just used old tennis shoes for the hike up the Narrows, but we probably only went in one mile. Maybe you would want something sturdier if you are going in farther. This was truly the most amazing hike I have ever taken! Have fun!