You need to go here to find out anything you want to know about mountain biking:
http://www.utahmountainbiking.com/UMBphpBB2/index.php
For a quiet, peaceful, road ride, try the Jordan Parkway Trail. Just find the Jordan River, there are trail heads everywhere. For a flat, easy ride, try the Legacy Highway trail. Immigration Canyon is a popular ride, with some moderate climbing. Send me an email and I'll give you a phone number to call me for more ideas and descriptions.