Use sunset as your turnaround alarm.
The name misleads people. You do not climb the Watchman, you climb the bench across from it, which is exactly why the view works: the Temples and Towers, lower Zion Canyon, and Springdale all line up at once. You can walk to the trailhead from the visitor center plaza, which means no shuttle and no parking hunt at either end. There is a short loop at the top worth adding, and almost no shade the whole way.
Underrated bench view of the Watchman and Springdale. Great first-evening leg stretcher.
Heat note: desert country - in summer start at dawn and carry more water than feels reasonable.
Water bottle, sunscreen, hat, snacks, comfortable shoes.
Official figures differ. NPS lists 479 feet of gain, plus about 80 more on the overlook loop (NPS). Our distance and gain come from GPS tracks, so treat both as approximate.
Make it a weekend: Watchman Campground (Camping, 0 mi) · South Campground (Zion) (Camping, 0 mi) · Lava Point Campground (Camping, 13 mi) · Kolob Reservoir (Fishing, 17 mi)
More hikes nearby: Canyon Overlook Trail (Hike, 3 mi) · Emerald Pools (Hike, 4 mi) · Angels Landing (Hike, 5 mi) · The Narrows (Bottom-Up) (Hike, 6 mi)