I lived in Barbados November 2002 - July 2004 and I am returning for 2 weeks in May.
Obviously, since I lived there, I don't know about excursions from the cruise ships. However.....
In my opinion the best place to see the green monkeys is at the Wildlife Reserve. Be sure to be there at 2:00. This is feeding time and all the animals (that roam free) gather to eat. The last time I was there, we probably saw 30-40 monkeys (up close and personal) including a tiny baby!!! There are also beautiful peacocks as well as the turtles (Beware of mating season - they are noisy boys!!) Keep handbags closed and watch personal effects because the curious monkeys are not above picking pockets and purses.
I went on many many catamaran cruises while living in Barbados. My favorite was Cool Runnings. http://www.coolrunningsbarbados.com/
There are 2 boats (Cool Runnings I & II). Cool Runnings II was brand new January 2003. I believe it can hold up to 80 (maybe more), however Robert never books more than 36. All the catamarans stop at the same 2 locations for snorkling. One is over a sunken ship (that also has zillions of beautiful fish). The other is snorkling with the sea turtles. Last time I was there, I saw turtles everywhere. They would swim within inches of us. Sorry, but if I do not know a specific species. The crew will tell you not to touch the turtles because they do not want them frightened away. An underwater camera is a must!! (Even the little disposable types do a great job.) Because all the catamarans basically cruise to the same locations and their lunch menus are pretty much the same, I base my recommendation for Cool Runnings on the FANTASTIC crew and the uncrowded decks. The regular day cruise lasts for about 5 hours. You stop at the 2 snorkling locations as well as the lunch stop (where you can swin ashore or just swim around the boat). Drinks (sodas, wine, Banks beer, & rum drinks) and lunch are included in the very reasonable price. The snorkling equipment and snorkle vests are also provided.
You can rent cabs for the day and you will have a good time.....however, I highly recommend the Island Safari tour. You will be picked up at your hotel in a 4-wheel drive jeep with an open back that seats 8. The jeeps all meet up and drive in-tandum to many locations not accessible via regular automobile. The drivers are very knowledgeable about island history. They are also very friendly and funny. They are always playing tricks on each other. The tour includes several stops for photo ops (and/or a little rum punch or sodas to keep you going) and a delicious lunch in Speightstown. You will be returned to your hotel. Like the catamaran cruises, this is an all-day adventure for a very reasonable price. http://cwts-bds.com/tours/index.cfm
I understand that if you book online, you can save 10%.
Hope this answers some of your questions. If you have others please feel free to write & I'll do my best to answer.
