I sailed the Legend in Oct 2005, and all I can say is she is a fantastic and beautiful ship. Service was superb, food was great and the layout is very easily navigated. One thing I will tell you, since you mentioned romance, you MUST do the Supper Club. Not only will it be the best meal you've ever had, but you can listed to live music and even dance if you feel the groove. The Supper Club is fantastic!!!!
As far as your excursion, in Cayman, I would NOT miss the Stingray Sandbar excursion. Where you go out to a sandbar in the middle of the ocean and swim with these amazing creatures. In Belize, you CANNOT miss the Cave-Tubing Excursion. Do not miss this!! Trust me, if you do, you will hear people on the ship talking about how awesome it is. Be sure to bring water-proof rubber-soled bottom shoes though.
Let me know if I cn be of further assistance. You will love the Legend. Great ship!! I'd be happy to share pics, let me know.