Ideally, you should spend a day at Bryce Canyon to see all the sights. If you plan on doing the Scenic Drive, you can complete it within an hour. However, that would be a disservice to the splendors of the park. If you take your time within 8-10 hours, you can do several hikes, have a picnic, and see all the majestic scenery the park has to offer. That said, you are certainly going to want to come back for more!