Depending on preference I have enjoyed the St Regis hotels in China for their hard product and service, particularly the resort in Lhasa - you can then tie in a trip to Tibet which is very interesting (I am presuming you would be allowed to travel there as a domestic tourist and child friendly as long as your kids enjoy culture and are old enough to walk around for at least half a day), otherwise as Frank says, anything on Sanya is the closest thing you will get to a resort from Marriott that feels like the US.

Personally in China I've always enjoyed the city trips more and would be stringing together multiple cities, with the high speed rail between them, staying at the best JW / St Regis in some of the major Tier 2/3 cities, may be less family friendly though.