They have 272 sites which can all be reserved - and often they all are. Each night we were there they were totally booked. However, the sites were reasonably private (in woods) and we were fortunate enough to have quiet neighbors - well, except for one early morning when some (probably drunk) idiot (in another loop) opted to start singing at the top of his lungs around 2:30am... His neighbors were understandably thrilled - but got him to stop eventually. I can't blame the campground on that one.
The location of Canyon is quite nice. It's on the Eastern side of Yellowstone - making it a super easy drive to the Hayden Valley to look at the big critters (buffalo, elk, etc). If you're there before August, you can also (supposedly) see bears quite easily by heading north from Canyon. In August, bears are harder to see as they move more towards berries. Waterfalls and their hikes are an easy drive too. You're farthest from Mammoth Hot Springs and West Thumb Geyser Basin.
One big hint about camping in Yellowstone - be prepared for 30 degree temperatures - even in August. The elevation is high - 8000 feet for Canyon. There was frost on a couple of our mornings... I'm glad we had mattress pads and cold weather sleeping bags! We did try out the showers - they're not metered, they cost a flat rate of $3.75 making them one of the priciest showers we paid for - but considering it's cold in Yellowstone overnight, they felt really good. If you need them, they also have coin laundry and a general store for supplies. All in all, I'd stay in Canyon again - though read on for my review of Norris as we enjoyed staying there too.
East Berlin, Pennsylvania
October 10, 2006
From journal 2006 Trip Pt 2 - WY - Devil's Tower to Yellowstone