How about the Grand Canyon followed by maybe 2 days in Sedona and you take the kids on a pink jeep tour? Or you could pair Sedona with Bryce Canyon although that’s farther. Bryce IMHO is positively grand canyon-like in majesty but with much fewer crowds, and you can go horseback riding at either Bryce or at Kodachrome basin state park nearby, and there are never crowds there. It’s a long way (maybe do an overnight in Las Vegas en route) but that area is the anti-LA in many respects.
Southern utah is also the only place I’ve ever been where I could not find a Catholic Church on a Sunday. I’m sure they’re there (like in Saint George) but when I went looking for one, I absolutely couldn’t find one.
Further both Bryce and Grand Canyon have modestly priced hotels right outside the park gates that are basically self-contained little towns. There’s a best western in Bryce that has a pool, shops, laundry, nightly entertainment, heck there’s even a rodeo across the street.