If you are limited on time, here's my suggestions from experience.
Arches – drive the scenic road, hike to multiple arches at
Windows Section, Landscape Arch. Delicate
Arch is longer, you can also view from below from a viewpoint.
Canyonlands – multiple entrances. If you only have time for one, I’d do Island
in the Sky. Hike to Mesa Arch. Stop at Dead Horse State Park on the way into
the park. Needles has nice views.
Capitol Reef – Drive Scenic Road
Bryce – Sunrise to Sunset Viewpoints, Queen’s Garden to Navajo
Loop (longer hike into amphitheater), scenic road with pull outs.
Zion – Riverside Walk, Sand Bench Trail, Weeping Rock,
Canyon Overlook – if you can get parking