Two years ago, right before our first cruise, someone started a thread entitled:
"What was your biggest thing your regretted NOT doing on your cruise."
Over 85% responded the same thing: NOT rebooking on board.
On Xmas day 2003 we rebooked for Xmas week 2005, and with the discount, credit and early booking rate, we paid $1,000 less for the second cruise than the first one!
I live by the rule "It is better to learn from others mistakes than your own!"
Jim