Last year we were first tier pricing booked for the Med, but ended up cancelling after I added up the excursion prices for a family of 5. My belief was why bother doing a European cruise if you did not do the excursions - espescially Naples/Pompeii/Sorrento, Rome and Florence. We had a 14 day trip planned - with before and after nights in Barcellona. Instead we did a 10day trip flying to London, taking the Eurostar to Paris and flying home. When we added up what we spend, it was just over 1/2 of what we had expected to pay for the cruise and everything else. (It helped that I have travelled to Paris a lot and knew how to get breakfast for 7 for only 11 to 14 euros

when the hotel would have charged 32 euros per person

).
Now our 3 DSs are in their mid teens and not as into Disney, we are on the doorstep of college and I went - WOW - I would love to do the Northern Europe cruise. Then my wife pointed out the price - nope. Not even tempted - which is a minor miracle.
We cruised the Carribean Princess out of NYC last summer, not only was the cruise fare cheaper, but we drove to NYC and skipped the horrible airport experience, had a wonderful time, on a ship built in the same shipyard as the Magic and Wonder. Our bill for a 11 day cruise was less than what a 7 day on the Magic would have been - and that is before adding in cross country airfare if we had done the Magic.
Yes the Princess service was not quite Disney, and yes I hate Princess Anytime Dining, but I lived with it.
We have reservations on Explorer of the Seas out of NJ next summer. Hopefully the economy picks up so we can do the cruise, but that is out of my control.
Do my DW and I wish we could cruise Disney - yes. We both still feel our best cruises have been on Disney. But, the combination of Disney Prices and airfares for a family of 5 make
DCL not an option.