From the sounds of things, you've set your sights on the all-inclusive option. With that in mind, both of the above properties sound pretty sweet, though I'd lean toward the Occidental Grand and its excellent range of kid-friendly amenities and activities. The beach at this resort is better, too. If non all-inclusives are an option, you might look at the Presidente InterContinental Cozumel Resort & Spa, which comes in with high marks from family travelers. The popular Iberostar all-inclusive chain also has a Cozumel property, which might be worth looking at.