I'm West-Coast biased. My favorites for families are:
GH Scottsdale - Great waterslide, artificial beach, lounge. So good I've visited 3 times.
PH Aviara - Fun pool area, waterslides, lost of theme parks in the area.
HR Huntington Beach - Nice small pool and waterslide area, and a pedestrian bridge connects you right to the beach
Suncadia - Great pool area with water slides, beautiful surroundings. No longer has Globalist breakfast.

No one has mentioned Hawaii yet, those are arguably the best for families.
GH Kaui - expansive pool/lagoon area, water slide, beautiful property
HR Maui - big pool area, on Kanaapali Beach, can feel busy
Andaz Maui - classy hotel with great pools for kids
I'll also give an honorable mention to Spirit Ridge in BC, 5 miles from the US border. Great for kids.

Places I haven't visited yet, but sound awesome
GH Indian Wells
HR Tamaya
HR Lost Pines
HR Hill Country