High: Penn and Teller, Stargazing at Grand Canyon Village, Antelope Canyon

Low: Crowds and heat at Zion

Surprise: Zion gets almost as many visitors annually as the Grand Canyon, but seems much more crowded.  Part of this is the park set up, as in the busy season almost all visitors are required to take the shuttle bus to hiking trails.  This is not unusual in US National Parks but this was the most crowded we have experienced.