To reach Zion from Park City point your vehicle west on Interstate 80. In order to bypass Salt Lake City (32 miles west) and its traffic-snarl potential, turn south on Interstate 215, a belt route that skirts the city from the east. When it rejoins Interstate 15, south of Salt Lake, turn left (south) and travel for 272 miles to Exit 27. Along the way you'll zip through Provo and Cedar City and pass Utah Lake, the Black Rock Desert and the Mineral Mountains. At Exit 27, turn left onto Route 17 and follow to the town of Leeds. Here, turn left on Route 9. Zion lies about 20 minutes ahead.
Before reaching Zion you'll have to option to pick-up the Kolob Terrace Road in the town of Virgin (located on Route 9). This wandering road climbs to over 8,000 feet as it dissects the middle of Zion, one of the least visited sections of the park. The Lava Point Overlook provides the type of views normally only seen in National Geographic Magazine.
In the town of Rockville, also off of Route 9, you can take a quick side-route to Grafton, a ghost used in Butch Cassidy and the Sundance Kid.