Cool thanks, yes I've got an iPhone 7 so I'll take a look at the app and see what I need to do to set it up if it's worth doing for out there! We're going to do a day tour to the south rim, which takes in the Hoover dam as well. Haven't booked it yet as seems like there are different choices.
its £££ but would always recommend the helicopter to do the Canyon due to the time it takes in a bus.