I would do Magic Kingdom.
-It's the most "classically Disney"
-It has the most "magic" feel to it
-Usually has the longest hours
-Lots of characters
-Lots of rides
-Lots of shows/parades/fireworks
It is a LOT of money, esp for a one day, but it's worth it if you're going to be able to get there for rope drop and stay til close, that's the big thing.
-Utilize your fp's and don't waste time on any TS ressos.
-As a group, decide which things are MUST do for you, which things you'd LIKE to do, and which things are MEH for you, if you pick 3 that you all agree on, use those for your fp (if availble) and prioritize from there!
Also remember that after a cruise you're probably going to be pretty tired, and pretty sun tired too, it might also be a good idea to have a nice sleep in at Pop, head on over to check out all the new stuff at Disney Springs during the afternoon, and then maybe have a nice character meal for dinner at one of the resorts to get some of the "magic" without the full cost. Head over to one of the monorail resorts to watch Wishes from outside the park and call it a day!