A great alternative when the Island in the Sky Campground at Canyonlands is full (or if you're just looking for something else up on the mesa), Horsethief Campground is a relatively well developed BLM campground. There are pit toilets, established tent pads, fire pits, and picnic tables at each site. I camped the first week of October and arrived after 5pm yet there were still several sites to choose from. The campground filled up as the evening went on.

Note that at certain times of the year there is NO WATER anywhere up by the Island in the Sky section of Canyonlands, at Dead Horse State Park, or elsewhere. Make sure you have enough water before you begin your ascent.

Horsethief Campground is a few miles away from the Canyonlands entrance and thus it's easy to get between the two in a matter of minutes. There are also mountain bike trails and hiking trails that leave from Horsethief campground. The views are incredible no matter which trail you take. 

I got up early in the morning to drive into Canyonlands to see the sunrise at Mesa Arch. It was beautiful and very much worth the early morning but it was also very crowded with other people to watch the sunrise.