My wife and I will be on the Caribbean Princess the week before you. If you fly into Puetro Rico early enough you can tour Old San Juan on your own, visting El Morro and Fort San Cristobal. Both are run the US Park Commission and the admission ($5. p/p) is good at both locations. If you arrive a day early you may also want to visit El Yunque Rainforest or the Bacardi Rum Distillery. (Liquor can be cheaper in San Juan then St Thomas but some will disagree. I guess it depends on what type you are looking for and since you are from NY you won't have to worry about the airline restrictions.)
St Thomas is know for two things: shopping and beaches. You can take a cab ride (rates are posted) to Magens Bay, Sapphire Beach, Coki Beach, or any other one of its magnificent beaches. Also Trunk Bay on St. Johns in rated one of the 10 best beaches in the world.
In Antigua we took the Nelson's Dockyard National Park Tour, which was interesting. In the afternoon we went to the beach on our own. They also had a casino at the foot of the pier where you dock.
Have never been to Bermuda so cannot comment.
A couple of years ago we took a repostioning cruise on the Grand from PR
back to NY. It's a real sight when you come back to NY harbor under the Verezano Bridge at 4:00 in the morning! We docked in Red Hook Brooklyn (How youuuu dooin).
My wife and I both LOVE Princess, especially any time dining. If you are celebrating a special ocassion you may want to eat in Sabatini's which specializes in Italian cuisine. Make your reservations as soon as you can to insure you get the day and time you want.
I'm sure after this cruise this will not be your boyfriend's last. Cruising is like a drug, once you start, you always keep coming back for more.
Have fun and let us know how you make out.