Zion National Park (Utah)
Zion National Park is absolutely stunning, however, it's packed with tourists so make sure to get into the park EARLY (< 8 AM).
We stayed in an Airbnb in Hurricane and drove the 20 minutes to the park, much cheaper than staying in Springdale.
We also recommend bringing your mountain bike and checking out the Gooseberry Mesa area. You CANNOT bike in Zion, this is a separate area outside Hurricane (https://www.trailforks.com/region/gooseberry-mesa-11991/?activitytype=1&z=10.1&lat=37.16227&lon=-113.20687).
Here is more information on Zion, https://www.nps.gov/zion/index.htm.