Famous around the World for its deep red cliffs, Zion National Park in Southwest Utah is simply spectacular. It is extremely popular year-round, specially around long weekends. Hotel/Motel prices in Springdale, AZ are sky-high while camping sites are usually booked many months ahead in full season. Cheaper accomodation can be found further to the east in Kanab area, but that involves 1 - 1.5 hours drive via Mount Carmel Junction.
Traffic in/out of park is regulated via shuttles. Angels Landing is the most popular hike and famous around the World. Since 2022 NPS implemented reservation system, and permits are - just like Half Dome in Yosemite, or The Wave in Coyotte Buttes - very difficult to obtain. I was lucky to do Landing twice before Reservation System took place. Other popular trips include Zion Narrows wading hike, best done late in season when Virgin River water level is low. Personal favorite is
Zion West Rim; simply awesome highline trail that climbs high above to Horse Pasture Plateau with spectacular views.