I visited Grand Canyon twice on this trip.  I stayed one night at a motel in Tusayan and on the return trip, I stayed in the Mather Campground (easily booked at https://www.recreation.gov).  

I enjoy the camping better than hotels.  The Mather Campground is a large campground, the sites are positioned close to each other, and my campsite did not have water or electricity.  If was a little walk to the bathrooms.  My campsite was reserved with only 2 days advance notice.  The website and signs at the check-in say that there are no walk-ups, however, some people were taking advantage of cancelations at the last minute.  

Even with these downsides of the campground, staying in the park was nice.  There is a general store close by with food as well as camping gear.  The Yavapai Tavern proved to be a pleasant place to enjoy a few beers and watch sports while the evening rainstorm passed by.