"We can't think of any passenger "demographic" that wouldn't find something to love on Crown Princess. On our trip, there were seniors, families, gay and lesbian travelers, honeymooners, and friends-and-family groups. The only folks who might find the ship's size a hindrance would be single travelers -- because of its size and its passenger capacity it can be hard to meet people." She is 113,000-ton cruise ship .
You actually asked "What Nationalities" use the ship. As you can imagine, the ship is open to ANY nationality that wants to book that particular cruise from their own country. However, obviously the port of embarkation will have a big influence on what the MAIN nationalities will be. I have just read a report that reports a lot of Spanish and Italian families on a RCI cruise from Barcelona. Exactly what you would expect. The same as you would expect a lot of Americans on a cruise sailing from Miami, or Brits on a Cruise leaving Southampton. We once cruised on a NCL ship sailing from Puerto Rico. Guess what that cruise had a lot of on? All you want to know about any ship will be detailed on the cruise company website or in their cruise brochures for future reference. Happy cruising.
Just a quick note to add to above. My answer was aimed specifically at the Crown Princess, which of course is owned by an American company (British until recently), so caters mainly to english speaking clients, in the same way that osta and MSC Cruises cater mainly for Italians. I hope that this helps a little?