The other issue to know about, with
Grand Staircase-Escalante, is the status of the roads. Many of them are either dirt or even 4WD-necessary type roads. The website for the national monument, which is cared for by the BLM, is reporting roads either covered by snow or currently very muddy. Your trip isn't until May, but I think you're better off spending extra time in
Zion. You need to negotiate the shuttle system, which requires a ticket for every person over age 2, and a mask on everyone. (I don't look for that to change any time soon.) It also takes time to work with the shuttle system, first for parking and then waiting to get around the park. One suggestion from one of my colleagues that loves Zion: "be prepared to wait a lot, and don't go back to the Visitor Center with your shuttle ticket until you are done for the day, because then you have to buy new tickets."
Donna