I would highly recommend Phyllis Taxi - we used her nephew Antonio Hayes (Kishorn), and he was the best! Get in touch with Seth @ Barefoot, we asked specifically for him for our time there, and they arranged it for us. You can read about our trip here:

Grenadines Sailing

If you want to do it yourself, you can reach him at tattoo_ah@hotmail.com, or antonio.haynes.560@facebook.com, or locally at 784-532-1554.

They have several vehicles, so I am sure it won't be a problem to arrange multiple trips to various locations. Very flexible and fun!

And Kishorn packs a mean grocery bag!