I just sailed on Explorer, and can tell you that drink card is not bad deal at all. It all depends what kind of drinks you like. If you are planning to drink imported beer and good wine at the bar than prepaid card may not be good. We used it mostly to get frozen drinks at the pool such as tango-mango, love connection etc.. You get 12 oz glass for $3.74. Bigger glass, I guess 16 oz cost around $7 with the tip. Regarding the size - most time on the ship your stomach will be pretty much full. Bigger size drink is not going to do you any good, if there not much room left inside of you.