While in Nassau you'll find some excellent excursions including the Atlantis Resort (located on Paradise Island), where a visit to the beach and/or the casino might be what you're looking for. Other options include the Historical Harbor Tour, a visit to Blue Lagoon Beach as well as other excursions chosen by Disney to enhance your time here.
The shorter cruises are a particularly good choice for those cruising for the first time. Many guests are concerned about how well they will fare at sea. These shorter cruises gives them a chance to experience a Disney Cruise vacation, and often leads to a "repeat" cruise.
The 3 and 4 night cruises are also very popular as an addition to a land-based vacation at Walt Disney World. Many guests start out staying at a Disney resort, and move on to finish their vacation with a relaxing 3 or 4 night voyage.