The key to staying away from the crowds while on a cruise in the Caribbean is to:
1. Get away from the dock before you get a taxi. There is usually a licensed association that has the rights to pick up the cruise passengers. They typically have bigger vans and will pile people in. If you get past them, you may find an individual driver that will take you where you want to go. The only place this didn't work for us was Barbados. But when we got to the taxi area (it's a long walk from the ship!) we told the dispatcher we wanted a small car for the two of us and she called someone up. Do a little research on transportation. On St Lucia, we thought we were in a taxi when a local got on and told us it was a bus- you can tell the difference by the plates, evidently. <img src="http://www.traveltalkonline.com/forums/images/graemlins/Blush.gif" alt="" />
2. Go someplace different than the cruise ship excursion spots.

Barbados: I asked our driver to take us to see the Barbados that would make us want to come back. We had an island tour including two very old churches and Bathsheba. Bathsheba is just stunning!

St.Lucia: Because all the cool stuff is in the south (IMHO)and it takes a REALLY long time to get there for a day trip, we went to Pigeon Point instead. Great hike, wonderful history. There is a beach there if you need one.

Antigua- Nelson's Dockyard!

St. Croix- I've never been, but I would get someone to take me to the Domino Club...

Okay, I live in an area with great beaches, so those down island don't interest me as much. I'd much rather see the historical sights and learn about some of the great sea battles that occured.