For me, the idea of a cruise was to have a great venue/room, easy food, and really pack in the diplomacy. I'm thinking three days max, for me, and we play every day. We're either playing diplomacy, eating or sleeping. Sure, maybe there's an hour or two that we schedule our diplomacy around something interesting, but far and away the point would be diplomacy.
If people are interested in a week long cruise where you alternate a day of play and then a day of diplomacy, that's great, but I'll wait for 2013 if that's the case... Or maybe we have a 2012 Dip Cruise and also a 2012 "Boston" sort of event in a city, so people could pick and choose (and those really into it could do both), assuming there is enough intererst for two separate events?