Most cruises sailing to the eastern Caribbean leave from Florida. The eastern Caribbean generally means everything east of Puerto Rico, which you can expect to visit, along with favorites like St. Maarten, San Juan, St. Kitts, Haiti, and St. Thomas.
The distance between the islands in the eastern Caribbean is smaller than that of the islands in the western Caribbean, which means you'll spend less time at sea and more time exploring the islands.
Excursions:
Some of the best shore excursions include ziplining through the St. Maarten forest canopy, kayaking through the Laguna Grande in Fajardo (the bay is full of bioluminescent organisms that light up as you paddle through them), diving in Grand Turk, taking in the view from Morne du Vitet in St. Barts, and swimming with the dolphins in St. Thomas.