An interesting concept. Of course, leaving from Southampton, the possibilities are many.
We actually had something similar on the West Coast a couple of years ago. Between the flu scare in Mexico and a couple of larger-than-normal Pacific hurricanes, if you boarded a ship in L.A. you were never quite sure where you were going.
I kind of like the idea since for me, the destination is really secondary to the ship. I would love to cruise on Saga Rose sometime.