Some of the best excursions we've done is a visit of the island from a cab driver for a negotiated price. They won't always take you to tourist traps,
penny - As long as you have an honest cab driver I agree this is the way to go in the Caribbean but , as we have recently read in the posts, sometimes one can run into very ruthless cabbies who will take advantage!!
I usually ask one of the local constabulary at the terminal to recommend a driver - and I've never had a problem!