Reading many reports about booking the next cruise on Board seems to give some good benefits. But can you book a "Generic Cruise" with Dates, Ports, And Ship left Blank until you can iron out the details later????
I'm not sure about not naming a ship, but you can book a ship and then change it without losing any of the benefits of booking onboard. You can also transfer the booking to your personal travel agent and not lose any benefits.
We just booked when on our last cruise with Princess on board. I know at the time we booked the cruise was in a promotion and we thought we got a good deal for a 10 day with a balcony. We didn't do air with them and are letting our TA do that for us. This is the first time we ever booked on board. It was painless, but as I said it was a promtion so it was a nice deal. Mary Lou is correct you can change the ship and destination without losing any money so that is also a nice feature. We only had to put $200.00 down instead of the $900.00 we would had to do if we did it with our TA. Our TA did get credit for the sale so everybody is happy :-)
Weve booked the last 2 trips on board and got some great deals. Our TA gets credit for them as well. It was nice to be able to see all of our options, what cabins were available (joining ones since we travel with my father and brother), the ships layouts, and ask detailed questions that a TA might not know right then and there.