Have you considered Jamaica? My wife and I have been there 4 times but only to an adults only AI. However, there are many resorts on Negril's side of the island that are right on beach. Said beach is pretty awesome. I think they have a Beaches resort there but I'm not sure about cost.
My wife and I took our 3 boys over Labor day weekend last year. As far as tickets, we purchased four 2-day park hopper tickets. The last ticket we bought the day that we checked into our hotel. We purchased one of the Universal Studio annual passes which gives you a discount on the hotel...