Anonymous wrote:We went to Joshua Tree for spring break a couple years ago. Stayed in an air bnb right outside the park. The kids spent time doing ranger programs, exploring the different trails, and tons of time just climbing the rocks. Then after we tired of that, it was an easy trip to LA to do non-national park things.

This is probably up OP's alley. If you're feeling particularly ambitious, you could also go to Channel Islands NP. Although it might be too rustic for OP.

End of March is going to be tricky. Many/most of the parks identified above will be too cold / snowy / closed.

We have 3 kids 6-13 and took an nice trip last year, also end of March, spending two nights in Tucson (Saguaro NP/Sonora Desert museum, amazing Mexican food), three nights in Sedona (including a day at the Grand Canyon) and a night in Phoenix at the end, where we flew out of. You can probably skip Tucson/Saguaro (my oldest loves cactuses and we are big NP people, so always want to check out the ones we can), and just do Sedona and Grand Canyon combo. Grand Canyon will be chilly but open, and Sedona should have great weather. You can stay in Sedona the whole time if you are OK to wake up early one morning and head out to GC for the day. Sedona has some great restaurants, cultural activities, excursions, very accessible and scenic hiking.

Arches/Canyonlands NP also would likely have good weather in March, but you would not have enough to do there for a week if you aren't into hiking every day (we are not either). We spent 2.5 days and that worked for us. We took a jeep tour in Canyonlands/dead horse state park, spent a day hiking in Arches, and then the third day we split up and some did more hiking and some went horseback riding. Moab is very small and there is not much there or nearby. You could combine it with a few days of skiing in Park City or Colorado.