Hi Ashkins,
My family of six was on the 4/6 Magic. The cabbies wanted $6 a head to get us to the beach (each way - tot. $72). We ended up renting a car for $70 for the day, cruised the island, and went to multiple beaches. If you're comfortable driving a car on the left go for it. We did the same on St. Maarten. This gives you much more flexibility and time to explore.