Do your kids a favor. Check out Pueblo Bonito Resorts. They just recently added "all-inclusive" to their Mazatlan Resorts. The security staff is always present 24/7 so we never had to worry about the kids hanging out by the pool while we were at the adult pool. It is a time share resort so be prepared for the sales pitch.
The Barcelo is great for kids as well. They have the resort seperated into families, mixed, and adults only. The kids section comes complete with a mini-water park and play area.