hi there! Congratulations on your engagement!
FI and I are getting married in St. Thomas in April 2012, while in port during our Carnival cruise, using Island Bliss Weddings as our on-island wedding coordinator.
When doing a cruise wedding you have a few main options:
1. embarkation day wedding - can include non-sailing guests, have to use the cruise line's wedding department.
2. mid-cruise wedding - shoreside or on ship, using the cruise line's wedding department
3. shoreside wedding at one of the ports, using an on-island wedding coordinator - this is what we're doing, so I'm biased. But its cheaper and you can have more planning control. As much control is possible for a destination wedding of any kind!
good luck with your decisions and happy planning!!