I concur with the above. There are not a lot of Jammers on this site.
I'm trying to think of the islands you will be going to. Mayreau, Grenada, Bequa, St. vincent will be the major stops I believe.
Grenada: Without a doubt book a tour with Mandoo. I believe Mandoo is back in operation from the hurricane. If so, do this before your vacation,
Bequa: I like the catamaran to Mustique. There are other tours but I would recommend the cat.
St. Vincent: Do the powerboat.