I'm glad this thread got bumped up because it made me realize I never posted our excursions! We were on the 10/18 Fantasy, first time cruisers, DH and I on our honeymoon
26/25 years old respectively. Going into our trip my DH's one request was no complete-beach excursions, as he is a textbook Irishman and pale as a sheet of paper.
St. Maarten: I had been to St. Maarten before with my family (we were not impressed) but DH hadn't, so I booked Bernard's Tours to give him a good once-over of the island as well as stops where I thought he would be most interested, Marigot and Maho Beach (we did not want to do Orient Bay, see above re anti-beach husband). The tour pick up was very convenient at the dock and we shared our van with about 10 other passengers, one family from the Fantasy and the others from the Carnival and Norwegian ships in port. The van was stocked with a cooler of water, soda, Carib beer and one heck of a rum punch which was included in our tour price, and we made good use of it! Our driver was friendly and spent the entire time giving us facts and history of the island. Unfortunately the island was hit by a hurricane 2 or 3 days before, and a lot of destruction was visible (boats on land, overturned cars). We ended up losing 30 minutes of our time in Marigot because of a downed power line from the storm, but there's nothing to be done about that - our driver cut Marigot short to make sure we would be able to make the big KLM plane at Maho Beach, which was the serious highlight. Other than Maho Beach and Marigot, the only other stops were scenic outlooks where we took photos, which we didn't mind. We stumbled back onto the Fantasy slightly buzzed from rum punch and very pleased with our experience!
St Thomas/St John: My one request was SOME beach time and that it be at St John and Castaway Cay, and because we were nervous about braving the ferry boat ourselves we booked the St. John's Eco Hike through
DCL (again, to appease the anti-beach husband). The ferry departed from the cruise dock again with passengers from other ships as well as those who had booked the Island Tour and Trunk Bay excursions. Once we got to St John we were next door to the National Park Center, where our .75 mile hike took off from, led by 2 different guides. The trail wasn't too bad in terms of difficulty, but I would definitely wear sneakers or something more supportive than flip flops. I would also bring a bottle of water for the hike (even if that means paying ship prices) and make sure you eat well that morning - DH came close to overheating and was not doing so well. Along the way our guides pointed out local plant and insect life and told us about island life in general. Honeymoon Beach is AMAZING and a serious highlight of the island - quiet, peaceful and pristine. We were greeted with cases of water and a selection of chairs ready for our group and enjoyed 45 minutes in the most crystal clear ocean I have ever swam in. From there we walked up to the advertised sugar mill, though we really passed by it rather than actually stopped and explored. From there we boarded taxis back to the St John port - the path from the beach to the taxis goes from sand to asphalt so putting your sneakers on over wet and sandy feet is not required (we threw everything into a spare plastic merch bag in our backpack) At the port we poked around the Park Center and local shops until the ferry came back for us. I would definitely recommend this excursion if you are looking to perhaps be a little more active on your trip or for more than JUST a beach excursion (and I would 100000% recommend Honeymoon Beach) as well as the security of knowing you are on a DCL excursion if you are concerned about getting back to St. Thomas on time and ferries that run on "island time".
As for Castaway Cay, we planned a day at Serenity Bay but were sadly rained out. I guess we'll just HAVE to cruise again!