I bought the Cocktail card on Explorer back in Oct. It wasnt a bad deal, overall, as it lowered my per drink cost by a dollar to two, BUT I can't remember what it cost! It was not unlimited but a set number of drinks, and your card was punched with each one.
In any case, I would not do it again, and in fact we had trouble drinking thru it. It covered only basic cocktails, using house brands. Fancier cocktails, such as drinks of the day, were not covered. And only the cheapest of beers, not the "imports". After a few gin/tonics, I started ordering my regular call brand, and since I prefer import beers, I usually ordered what I like. Hey, I'm on vacation! So, if you like Bud, and house wine and liquor are ok, its a good deal.
As for the wine list, I am no wine expert, but the wines they offered looked good, and it wasn't jug wine, etc. There were a few programs on offer, that provided different numbers of bottles. I dont recall seeing a premium package, specifically. Don't worry though, you can easily book on board, as there will be tables set up outside all of the eating areas on the first couple of days that showcase the wines and sell the cards. As I recall, there were some tastings too.