I found a lot of information over on cruisecritic.com for our cruise. Here are a few recommendations from cruisers:
Barbados: Glory Tours http://www.glorytours.org/
Silver Moon (we are doing this one.) http://oceanadventures.bb/sailing.htm
St. Thomas. Here is a site with a wealth of information: http://www.vinow.com/
San Juan: We have been there 3 times and really enjoy taking a taxi up to El Morro and then walking our way back down through Old San Juan. Here is a link to a walking tour guide: http://www.frommers.com/destinations...323010008.html
and a guide to Puerto Rico: http://www.gotopuertorico.com/
I haven't been to the other islands lately.
Have a wonderful time planning your cruise!