I've been out riding and running on many trails around Moab and the one that totally blew my mind was The Whole Enchilada. http://vimeo.com/2955619
It's simply amazing! A longer bike ride that starts with a shuttle ride from a local bike shop up to the top of the La Sal mountains behind Moab. The ride covers alpine single track through the aspen and then into the foothills with tall oak brush and finally drops into the desert slickrock. If your a decent rider there is no other option but to ride The Whole Enchilada. I've been to Moab about 6 times and love the traditional "trendy" Slickrock trail above town for a quick ride. And for that matter all the rides are fun. The Enchilada just will blow your mind every mile of the ride. So like 30 mind bombs. Oh and it's like 95% downhill so not too killer on the legs.