I just wrote a long post about a similar situation in the past day:
http://www.3fatchicks.com/forum/idea...-while-ip.html
I think the fundmental question is just how disciplined are you? When you read the post above, you'll see I went on a pretty decadent trip (part land, part cruise) and did a very controlled phase off (2 weeks P2, 2 weeks P3) in preparation for the trip and then I had whatever I wanted on the trip. First full day back I went on P1 again. Read the post for the details.
If you have great discipline and choose to stay OP, there's no easier way to do it than on a cruise - there's everything you need, as basic as can be (as well as everything else - but just ignore all other foods). If you aren't that disciplined in the face of constant temptation, then phase off carefully and do the best you can BUT get right back on P1 the first full day back home. You will be glad you did.
As Scorbett said, too many people take a trip, go off program and never come back, so sad...make a responsible choice, you are worth it. And remember, you can always have the food later (after you reach goal) that you are giving up now - there's that "fun meal" in maintenance every week.