As suggested, do not limit yourself to Zion only, pending your available time. Bryce is amazing. And, use the west entrance to Zion as stated.
A great strip to run is start in Moab, UT. There are days of amazing things to see from there: Arches (need several trips at morning, then sunset), Canyonlands (both from just outside Moab plus south a few miles of Moab - camera freaks will go nuts), Dead Horse State Park, perimeter run just outside Moab. Then head west to Capital Reef for an overnight - - get there early for a campsite and browse. If you have time, consider heading south into the Glen Canyon area - - great scenery. Then head to Bryce where you land on the moon (teasing - - amazing scenery). Horseback ride into the canyon is great plus terrific views of Grand Canyon from the north side here. Finally head on to Zion. We spent almost three months in this area adding in time on the south side of the canyon. So much to see and do. Don't rush. Enjoy. Take your hiking boots, cameras and binoculars. Have fun.