I really enjoyed the GH Indian Wells in the Palm Springs area (California). Pool areas are really nice for kids, and you can easily do a day trip to Joshua Tree NP. Main issue is that summer would be really hot though, so it's probably more of a winter escape. Also it's going from cat 5 to cat 6 at the end of the month, though I'm not sure you can book that far out in advance.

If the children are into museums/history, you could look into GH Washington DC. Definitely a very different vibe from HR Coconut or GH Indian Wells, but there is a club lounge there and rooms were recently renovated.