The Leprechaun Canyons are many people's first canyons. Easy access, and relatively straight forward, they are a good choice. Even a few scenes from the movie 127 Hours were filmed here, just below the confluence of the middle and right forks, in a stunning cathedral type section. This is one not to miss, and one of my favorites in the area. Choose your fork wisely if you are a beginner, the middle fork is tight and harder than the left or right.
Note, those that are not technical canyoneers can still enjoy the canyon from the bottom. The hike up, staying in the bottom, visits some astounding narrow and slot sections. I've done the technical sections a few times each, but have probably walked up from the bottom a couple of dozen times with non-technical groups. It is astounding. One small falls, when coming up from the bottom, is class 4 to circumvent, but it is otherwise easy going to the junction of the right and middle forks. A great leg stretcher if passing through the area.
WARNING: Middle fork is VERY narrow! This is not a good place for claustrophobes, or large boned canyoneers. Canyoneers that are larger than myself (6'2" / 170 lbs) may have to go high over several tight spots, increasing the difficulty. You have been warned! Although you can generally go high, it often is difficult to get above constrictions, and the rock is very crumbly and unpredictable.