I know if you buy multi-day tickets adding additional days is considerably less expensive than buying a single day ticket. I know when we were there 3 years ago if we wanted to add an additional day we could do it for whatever the difference in price between a 5 day ticket (which we had) and a 6 day ticket. I think we had to do it before the end of the day the last park day, but I don't remember. Can you still do it and if so, am I correct that we can do it by the end of the last day or is it before entering the last day? We currently have 5 day tickets, but for an additional $10/person/day we might spend a morning at AK before we go home, but we will probably wait until the last minute to decide to determine how tired and broke we are. 
