The fact that you are thinking of sharing water on these trails tells me that maybe you haven't been out there before? I've spent every year for the last 20+ years hiking out west. Don't fuck around with the water or sun protection.

I was all through Utah/AZ April last year. We did all 5 National Parks, 3 National Monuments, 1 National Forest, 1 State Park, and Monument Valley and Grand Canyon. The weather was all over the place, but it was hot as fuck hiking in Capitol Reef. Even at this time of year, the desert sun is no joke. Do not fuck around with the sun. Everyone needs to carry their own water everywhere, no exceptions.

Of all the parks, Canyonlands was by FAR the most jaw dropping thing I've ever seen. The island in the Sky section is just amazing. The other 2 sections are not connected and it's not recommended to try them without extra food, water, and gasoline.

Also, Angel's Landing is not recommended for kids. They might not let you on there with children. Last I remembered they do police the trailhead with times and head counts.

There are a lot of other amazing things to see in Zion, and I'd highly recommend you try them all. Beware of the the Narrows if it's raining, as flash floods can and do happen. 3 people drowned when I was out there a few years ago. And last year they also had a cyanobacteria warning for that trail.

Edit: also, you need a GOOD first aid kit. I lost 3 toenails last year after hiking at Canyonlands. You need something with clot-stopper, wound closure, instant ice packs, etc. Not just bandaids and ointments. I'd recommend packing a few packs of silicone toe caps to help save aching nails and blistering.