St. George has over fifty miles of paved paths for biking or walking. The city has made these nice and safe, going under crossroads and having some nice scenery. Here is a map.
At all the junctions there are signs to tell you the name of the trail and the nearby attractions. Periodically there is also a map available.
The photos below are parts of the Virgin River and Santa Clara Trails.
Here is more information on the different trails.