I would recommend the Grand Floridian one just because my soon to be granddaughter, at the age of five, did that on her first trip to Disney World and loved it. She had just been introduced to her new family (her mother is now my daughter-in-law) and we surprised her with the trip. It was just her and no siblings (she now has a brother and a third sibling on the way) so her mother was very anxious. The entire process is relatively painless for the adults and yes, the kids do get off the ship to hunt for treasure. However, before any pirate gets on the ship, they are matched up with a fellow pirate and those two will do things together. For my granddaughter, since she was on her own, she was matched up with a similar pirate also on her own and about the same age. When they got off the ship, those two were friends so nothing bad there. I can't tell you too much about the actual adventure because our granddaughter just smirked and said "all pirate have secrets" but my daughter-in-law and I did the monorail ride around while the adventure was taking place since my daughter-in-law was nervous about letting her, at that time, one and only, go off by herself. So, we did see when the ship docked and then my daughter-in-law, on her first trip Disney World, gave a huge sigh of relief and said, "I knew I could trust Disney".
One note - the kids, er, pirates, cannot exit the ship unless a parent/adult is there with the receipt so make sure you are back there in plenty of time for pickup and, er, um, just be there early and be ready to film when the ship backs into the dock. That's all I will say about that part of it.