Nassau has plenty of shopping and we loved the Blue Lagoon Dolphin Experience we did a year ago. This time we just walked to shops and Junkanoo beach which isn't great but it's free. Rocky bottom and glass on the beach. Nice view of the lighthouse and ships.
Not sure why you would do an excursion here! Just hang out and enjoy paradise! We've been to 5 islands in Hawaii, Grand Cayman, Jamaica, Nassau, Grand Turk, Key West and this is by far the nicest beach we've ever been to! We hung out in a hammock and dreamt of living there!