The Observation Point Trail in Zion National Park is an easy maintained trail that leads to a grand view of the canyon. The trail head is just east of the Pine Creek Tunnel on Highway 9. Unfortunately, the Zion Park system of buses does not run along highway...so you have to drive.
The overlook trail runs along Pine Creek Canyon, which is a slot canyon enjoyed by canyoneers. To visit Pine Creek, you should hire an experience guide to set up the many rappels you need to take through the canyon.