Use sunset as your turnaround alarm.
This one sits outside the park's main gate, four miles east on Highway 12, so you skip the entrance line and the rim road entirely. It is under a mile round trip along a creek to a waterfall and a damp alcove that grows icicles in winter, and the whole thing takes well under an hour. You still need a valid park pass in the vehicle. Get in the water at the bridge crossings only, not wherever looks good.
Hoodoos + a waterfall the kids can splash near, no rim driving needed.
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 0.8 miles round trip with about 150 feet of elevation change (NPS). Our distance and gain come from GPS tracks, so treat both as approximate.
Make it a weekend: North Campground (Bryce) (Camping, 4 mi) · Sunset Campground (Bryce) (Camping, 5 mi) · Sevier River (Upper) (Fishing, 18 mi) · Wide Hollow Reservoir (Fishing, 27 mi)
More hikes nearby: Fairyland Loop (Hike, 2 mi) · Queen's Garden + Navajo Loop (Hike, 4 mi) · Peekaboo Loop (Hike, 4 mi) · Angel's Palace (Hike, 12 mi)