I wonder if they let you buy wine by the bottle at dinner and bring the left over to your room?
When we went to the wine tasting on Princess, the entrance fee was $5, which was applied to a moderately priced bottle of one of the wines that we tasted, liked and bought. We didn't want to drink the whole bottle at dinner that night, so the waiter had it held for us so we could finish it another night. And that was in the Personal Choice dining room where we didn't have the same waiter every night. I don't know if Carnival has a similar arrangement.