THIS WAS SO FUN! My brother just moved to Phoenix so on our first visit over the summer we did this. I literally cannot wait to do it again! You float down a river with booze and food, with absolutely stunning scenery... what's not to like? There was some trash in the river, which made me sad, so we tried to pick up anything we could grab.
This is such an inexpensive, fun activity. Obviously there is the potential to have a big party but we saw lots of families too!
If you're a noob like I was here are some things you should bring along:
Water shoes - do not underestimate the importance of these
Cooler with food/drinks
Sunscreen/hat/sunglasses
Rope/cord to tie your tubes together
Cheap sheet to tie over your tube (they're black and the sun is hot)
Water tight box for your phone
Trash bags
Waterproof speaker
Bag of marshmallows if you want - some people like to throw these!
Have fun, be safe, and clean up your trash!