For beaches
Bus to Grand Anse, Grenada
Taxi to Spice Club, Bonaire
Share minibus to Carambola Beach Club, St Kitts ( or day trip to Nevis)
Taxi to Boatyard (expensive and crowded) or Harbour Lights (cheaper and quieter) in Barbados
More to Caribbean than great beaches though, especially if new to the area.
Enjoy your trip.