I booked without free at sea on my prior sailing. About a month out, the price dropped for a slightly upgraded cabin with the drink package. Norwegian will gladly let you upgrade your room, as long as the upgrade costs money.    For example, if my original booking was $2000 (no drinks), and an upgraded cabin with drinks costs more than $2000, I can pay to upgrade and get the drinks package.    As long as you don't need to book a certain type of cabin, like an aft balcony, the