We heard from a friend, that surely Grand Canyon is a must-see, since it's the only thing like that in the world, however there are even more beautiful places on our way. Zion is one of them.
Rock formations create not so huge, but beautiful canyon, with lots of opportunities to hike and rest. One of the dangers there is flash flooding, which can happen when there's sudden rain and smaller parts of the canyon can fill with water, mud and rocks really quickly.
It's still a desert, however the altitude is fairly high, so the it's not always that hot. One thing I've noticed is that their visitor center is build in a way, that enables them to take advantage from the cooling wind and heating sun for different times during the day, so they have completely passive heating and cooling system. It's possible only in this specific climate, but still, looks really impressive.
Next: Bryce NP