Uhhh... I can't believe no one has mentioned Park City, UT. There's only 300 miles of marked and maintained true single track right out your front door. No driving necessary. There's some OK DHing at Deer Valley (5 - 15 min from PC), and the Canyons is building a true lift accessed terrain park for 2012 (started late 2011 and was a huge hit). There are two official public stunts trails (built by city sponsored organizations), and a couple other semi-secret. There's a large public DJ area and 3 or 4 pump tracks. During the winter if you don't like skiing/boarding (which is world class), they maintain XC ski trails and allow biking on them.
Lastly, if you don't want to live in PC you can live in Salt Lake City, and all those trails are only 15 - 30 mins away. I drive up 3 days a week to riding in the mornings with no complaints.
Lastly, if you don't want to live in PC you can live in Salt Lake City, and all those trails are only 15 - 30 mins away. I drive up 3 days a week to riding in the mornings with no complaints.