As best I can tell, they exist for some itineraries and not others. If it's going to be there, it will be on that itinerary page after you've chosen a date and hit 'Continue.' I remember I didn't have one for our cruise earlier this year that had had its itinerary changed, I assumed they didn't want to make a new one. I do see one for our Wish cruise later this year, on the main reservations page about halfway down. I'm not sure what the rhyme or reason is for which ones have it and which ones don't.