Use sunset as your turnaround alarm.
This is the trail that ends where the famous one begins. A mile of pavement runs upstream from the Temple of Sinawava, the last shuttle stop, and stops at the point where the canyon pinches down and everyone else steps into the water. The park lists it as wheelchair accessible with assistance, which is rare here, and the grade is gentle enough that kids can run it. Go early or late if you want the hanging gardens without a crowd moving past you.
Paved path to the Narrows entrance. Squirrels, hanging gardens, river access.
Heat note: desert country - in summer start at dawn and carry more water than feels reasonable.
Water bottle, sunscreen, hat, snacks, comfortable shoes.
Make it a weekend: South Campground (Zion) (Camping, 6 mi) · Watchman Campground (Camping, 6 mi) · Lava Point Campground (Camping, 8 mi) · Kolob Reservoir (Fishing, 12 mi)
More hikes nearby: The Narrows (Bottom-Up) (Hike, 0 mi) · Angels Landing (Hike, 1 mi) · Emerald Pools (Hike, 2 mi) · Observation Point (East Mesa) (Hike, 3 mi)