As already mentioned, mixers do not count. We have done several cruises with HIA (Have It All) with the Signature drinks package. Even with cans of water, diet cokes, lattes etc wine at lunch and dinner and in between and a brandy or two before retiring, we have not hit 30 drinks between us.
For any drink over the $11 limit you will be charged the overage plus gratuity on the overage.