Check out Carib Tours. Personally, I would opt for Barbados or Antigua as they are the larger islands. There is all sorts to do from swimming, water sports, trips out on a boat, dining, shopping, and history. If you are interested in the people and culture both these islands are rich and of course the music scene if you are into reggae etc. You could hire a car but the bus service is also good. Make sure you take plenty of sun tan creme and mozzie repellent. And, it is hot! So, wide brimmed hats, good sun glasses and light airy clothing. We had a ball and used to go twice a year. We stayed in Holetown in Barbados on the west coast which had a good bus service into Bridgetown. St Lawrence Gap had a good night life and the east coast for surfing.