Rafting
Lots of people want to do it, and the number of trips are limited. Plan as far ahead as you can, but don't give up if you're planning with only a few months or weeks to go. Cancellations happen all the time.
Mule Rides
The most popular way to get to the bottom of the Grand Canyon. You'll need to reserve not only the mule ride, but also the overnight stay at Phantom Ranch, as far as ahead as you can.
Lodging in the Park For locations outside the park, you have a little more time, but if you want that special room at El Tovar, you'd better reserve early.
