Island Cruises are informal (similar to OV) and cover quite a range of Caribbean islands. You may find Island Escape too small and even the larger Island Star is smaller than the OV ships. Island are a British based operation and offer flights from a range of UK airports. The flights are chartered by them so you go direct to Barbados rather than possibly being put on indirect flights by some of the US based operators. Food is on a buffet basis with less choice than OV (not so many Indian/Chinese/Thai etc options) but still very nice. You can pay extra in the excellent Steak House and Oasis restaurants. I suggest you get a brochure to get a better idea of what they offer. Hope this helps.
I would suggest RCI's Adventure of the Seas out of San Juan - the southern Caribbean itinerary is pretty intensive and you will get 5 islands in a 7 day cruise. Alternatively, if there is any space left, their Vision of the Seas out of Santo Domingo does a 14n cruise with only about 2 sea days. Enjoy.
If you like an informal, lively party atmosphere you should consider any of the Carnival ships. Otherwise, Royal Caribbean or Princess offer plenty of entertaining options, but with the option of dressing up on a couple of nights but you can still dine without the need to wear those "glad rags". In addition I can recommend Disney cruises, plenty of children on onboard, but rarely any bad behaviour coupled with some of the best food available outside the luxury end of the market.
I've booked a cruise on the Sea Princess for 13th December 2008. The name of the cruise is Caribbean Islander (Cruise Ref. 2419478). This is a 14 night cruise departing from Barbados and only has 2 days at sea. The places to be visited are: Barbados, Dominica, Antigua, St. Martin/St. Maarten, Tortola (British Virgin Islands), Samana (Dominican Republic), Montego Bay (Jamaica), Curacao (Dutch Antilles), Bonaire (Dutch AntilleS), Isla Margarita (Venezuela), Grenada, Port of Spain (Trinidad).