Yes, I am now a Tool of the Mouse.
It's difficult to conceive, without being aboard, how huge a cruise ship is. This thing is about 1115 meters long, and has a gross tonnage of 130,000. There are 14 decks of various sizes, and 1250 staterooms. Inside, the decor is Art-Deco, and beautiful as can be. I love the style of that period, and lament that we no longer really make things of the quality evinced during that period. Disney, of course, being gigantic, rich, and all-powerful, can afford to do this stuff right, and the craftsmanship of the vessel is amazing. I can only imagine how impressive such a ship could be if it was ten (or a hundred) times as large.
Oh, and I also managed to buy some six-sided dice while aboard. The pips are little mouse heads.
So, mini-review: The cruise was a 7-day, Western Carribean trip, with stops at Grand Cayman, Costa Maya, Cozumel, and Castaway Cay. We did some dancing and drinking, rode in dune buggies, did some swimming and snorkling, and ate way, way too much.
The staff of the ship ("cast members") were the best I've ever seen in any customer-service situation. It's amazing how good they are. The ship is clean and well-maintained. I don't think I ever saw any real mess, and the bathrooms were impeccable. As soon as we left the ship, you could see the difference. We had a seven hour drive back to the house, and the bathroom breaks along the way were... frightening.
The food is good (if way richer than I usually eat--I think I gained like 10 pounds). The drinks are not too terribly expensive, and poured in sufficient strength to get the job done. The wife and I even went to their fancy restaurant (Remy) on the first night. I've never done such a thing before, but decided to go whole hog. We sprang for the "wine experience" and, in the end, I dropped 500 bucks on a single meal. It was worth it. I know that's insane, but it really was worth it. Every course (9 in all) had its own wine. Each was delivered with great ceremony, by at least 3 cast members, and our server (a cute Polish girl) and wine steward (a frightfully elegant French woman) were amazingly good at their jobs. In the end, we were replete with food and drink, and our asses had been thoroughly kissed. I've never in my life been lavished with such attention. I can see how that sort of treatment, every day, could tend to corrupt one's expectations and sense of place in the world. I, of course, don't have the option to have that sort of life, and will (sadly) avoid such an outcome. For me, it's back to being on the other end of the stick, dealing with bratty students and idiots of all stripes, and living from paycheck to paycheck (and, of course, paying off the now-bloated credit card balance). Lifestyles of the not-so-rich-and-famous, if you will.
I guess the only thing that I wish there had been fewer of would be the other passengers. The Great Wad of Humanity was something to see (and sometimes not in a good way). If I never see another 50 year old guy with a shaved chest, wearing gold chains and a "banana hammock," chatting up the female staff, it will be too soon. I'm not that great with crowds to begin with, so that part of it was... challenging, at times.
Okay, so I did that thing. It was fun. I might even do it again, some day. Now, here's the gaming part of it.
I spent a lot of time, while on the ship, just wandering around and admiring the scenery and architecture. At one point, I tried to imagine the ship devoid of people. It was pretty creepy. An empty cruise ship of that size (let alone something bigger), even with sufficient lighting and in good upkeep, would be a weird place, with all kinds of places for traps, creatures, and whatnot. With 1250 staterooms to clear, all of the various bars, restaurants, and public spaces, you have a pretty respectable megadungeon to deal with.
If you want to go with a nautical theme, then you've got not only the usual sorts of monsters to stock it with, you also have the ocean itself, and its denizens. On the other hand, if you wish to do it up as a space-based adventure, or perhaps a post-apocalyptic one, then the ship could be adrift in space or buried in the silted plain of a ancient seabed. This would, of course, change things you might encounter, there.
Most importantly, you have a variety of pre-existing maps to choose from. Here are a few to start with:
The ship I was on: http://www.cruisedeckplans.com/DP/Main/decks.php?ship=Disney%20Fantasy
A Holland-America ship: http://www.hollandamerica.com/main/DeckPlans.action?ship=na
The Titanic: http://www.encyclopedia-titanica.org/deckplans/ and this one too http://www.copperas.com/titanic/
You would, of course, have to key the maps to do whatever you wanted them to do (creatures, traps, features, etc.), but you would be working from real plans, of real, working ships. This would limit the need to invent from whole cloth, the various things one might find.
Give the various plans available, it would also be relatively easy to mix and match different ships' plans to achieve your ideal form. Or (and this seems like a fun idea), you could use multiple ships at once--Maybe they are in a harbor somewhere, or at a space station, or whatever.
The important thing, though, would be to use them as the background for whatever you wish to accomplish. I like the idea of treating them as dead places, forgotten crypts, ancient constructs, and such things as that. You could just as easily use them as fully-functional and operating ships, with crew and passengers, for some other sort of game (not involving any dungeon crawling, or such activities).