Finding spectacular hikes in Zion National Park is pretty easy (Angel's Landing, Hidden Canyon, Observation Point), but most of them require a shuttle trip from the main parking area near the visitor center. Watchman Trail is a great short hike that can be reached on foot from Watchman or South campgrounds or via the town shuttle.
Starting near the bridge that crosses the Virgin River (on the south side of the river), the trail follows the river for a short way until it branches off and starts to climb the slopes below Bridge Mountain, losing sight of Watchman. Keeping up a steady climb on several switchbacks, the trail crosses the creek and climbs up another ridge, where views of Watchman Peak start to come into sight for the first time. The trail reaches a signed junction with the loop trail, and this circles the top of the ridge, offering one spectacular view of the Watchman after another. There are also nice views looking up the main Zion Canyon and across to the Towers of the Virgin.