We've done the 4 night cruise twice. I don't remember the Pirates Party, but it's been a few years, maybe they have it now. There was a "formal" night - ours was the night we went to Triton's. We also ate at Palo, which is "dress-up" - but Disney ships are notoriously casual - even "formal" night at best meant maybe a sports jacket for men - no ties are required even on formal night. I'm sure they have the romance package. You'll have a great time - our favourite part is Castaway Cay. Head for the adult beach "Tranquilty Cove". The water is so clear you don't need snorkle equipment - just walk along and there are tons of fish. An Atlantis tour in Nassau is a good option - we took a short morning one and had the afternoon to go to the beach there, roam the resort or downtown Nassau.
Don't miss any of the entertainment if you can help it - especially the "Awards Night". Choose the late seating and then you can do the entertainment before dinner, leaving after dinner for a nice evening in one of the clubs.
We never felt rushed at all on the 4 day. Enjoy it!
