I work those days, so I can't join you for a ride, however I'd be happy to help you out with trail info.
www.utahmountainbiking.com
This site has the majority of local trails listed on it and you can search through the St. George or Gooseberry (Virgin/Zion) areas separately.
My personal favorite loops in town are Zen Trail and Barrel Roll. Zen Trail is technical with a pretty good climb to start out and it is easy to get confused on your first time out. Barrel Roll is much more straight forward, has some technical riding and some great fast sections. It is also a little more straight forward as far as navigation goes.
Don't know if you like to climb or hike, but Zen Trail is next to Zen Wall and Green Valley Gap, two excellent spots for sport climbing. Zen Trail would make a nice hike as well.
Barrel Roll is just up the road from some awesome rock art.
http://www.petroglyphs.us/photographs_petroglyphs_anasazi_ridge_utah_AR.htm
This is right down the road and a pretty good diversion. I'd plan on spending an hour or two out there if you go.
If you want slick rock, Church Rocks is a decent option near town. Making the drive out to Little Creek, Gooseberry, or Guacamole Trail is well worth it. I believe Quentin at Over The Edge Bikes in Hurricane does a weekend group ride out there. Even if he doesn't the guys at that shop are awesome (Hi Dave!) and will point you in the right direction.
Have fun on our trails! They are way different than anything you'll find in Minnesota. Moving here from back east the lack of trees and plethora of sharp pointy things took me a while to get used to.
