When I booked on board, I had my reservation assigned to Beth F. at Dreams Unlimited. They give OBCs based on length as well. She has been great to work with. You can see their on board credits here. http://www.dreamsunlimitedtravel.com/cruise/specials.htm
I have used DU now twice, and both times, I have gotten excellent service.
Great! Thank you very much for the information!