For the last ten years I have kept at least 100 shares of Carnival and Royal Caribbean in my portfolio.
I have received the OBC on just about every CCL and RCI cruise I've taken in the last ten years. I wasn't eligible one time and it was because of the fare that I booked. I can't remember, off the top of my head, the exact reason but it was on a Celebrity cruise.
I just received confirmation of my OBC for my upcoming Celebrity, Millennium cruise. That combined with my Amex Platinum cruise credit will help with the bill.
You do have to send in a copy of your monthly statement or a proxy statement but that's about it.
I wouldn't go out and buy 100 shares just to get the credit but if you have a diverse portfolio you can do a lot worse than having a couple hundred shares of cruise line stock in it.
BTW: CCL stock will cover all CCL lines: Carnival, HAL, Princess, P&O, Costa, Seabourn etc.
RCI: Will cover Royal Caribbean, Celebrity and Azamara.