Snow Canyon State Park is a hidden gem. Being a little overlooked due to the proximity to Zion National Park, but is most definitely worth checking out. You won't have the crowds and the scenery is what most would describe as amazing.
From St. George:
Head north on Bluff Street.
Turn left onto Snow Canyon Parkway.
Turn right on Snow Canyon Drive.
Just before the pay booth, there is a dirt parking lot. Start here.
Riding the trail...
You will begin by heading up the paved bike path. Follow the path until you see a dirt road heading out on your left. This is the West Canyon road. Follow the road as it takes you up the canyon and enjoy the solitude as you will most likely see no one. If you go in the evening, you will be treated to some astonshing colors and quite possibly some coyote howls.