This vacation island off the coast of Massachusetts is more than just a rhyming word for dozens of off-color limericks. In the summer, its population swells 5-fold as vacationers come for its sweeping beaches, flowers and seafood restaurants. The oldest operating windmill is on the island whose earliest residents were whalers. (Ahab and Starbuck in the novel Moby Dick hail from Nantucket.) Book your ferry or airline ticket early -- in the summer, the local airport sees more takeoffs and landings than Boston’s Logan.