Don't skip Zion!
We've been to most national parks and Zion is a favorite.
"On April 12, 1995, heavy rains triggered a landslide that blocked the Virgin River in Zion Canyon. Over a period of two hours, the river carved away part of the only exit road from the canyon, trapping 450 guests and employees at the Zion Lodge." Quote from Wikipedia.
This event was reported on by a trapped newsperson. Who did not really want to be rescued as they had been enticed with the charm of the park.
This triggered lots of interest in the park which never subsided and resulted in the shuttle service starting in 2000.
Believe me before the 1980's the park without many people was even more wonderful.
We have a picture of our 50 year old son drinking an orange soda there when he was about 4.
Even broke my arm in Zion on a family camping trip in the early 1950's, I was just 7 or 8.
Would never pass an opportunity to go back.
Well maybe I just have a lot of good memories of a spectacular place.
On Edit:
A fun thing to do at Bryce Canyon is to stand at Sunrise point when a tour buss unloads and listen to the gasps when people see into the canyon for the first time.