Punta Cana is proably the least expensive place in the Caribean - it is perfect for all inclusives, not perfect for sightseeing, it is a poor country, but the resorts are safe, beaches are beutiful and you get the bang for your buck!
Not only great prices, but a great places to take the entire family

Here are a few examples I found that have really good rates -
this deal ends 2/27 $549+: 3nts Sunscape Punta Cana w/Air
click here - http://track.dunhillvacations.com/q/?e=11993/u/1754421

Jamaica is also another island that has tons of all inclusives for families - this includes, kids activities, all your food and someimtes alchohol.
If you clcik here, you will find a buch of all inclusives all over the Caribbean:
$258+: 3nts All-Inclusive Resort Family Getaway - click here: http://track.dunhillvacations.com/q/?e=12017/u/1754421