A short personal story on the topic: In the social circles that I hang out in, a glass of wine or beer (or more) on a night out is pretty much the norm, and I've lived by that lifestyle ever since I reached the drinking age 14 years ago. I have considered giving up drinking for a few months now and decided to go slowly at this challenge this year, by first taking a 3-month complete alcohol fast, just to test what it's like not to drink at all. What I have recognized so far is that only by not drinking any alcohol whatsoever I can trust my mind completely. And if I want to be serious about understanding the workings of my mind and eventually uproot even the most subtle defilements, hindrances and cravings, I must develop a lifestyle that enables me to maintain a lucid and perfectly aware mind at all times. In addition, if I'm serious about my daily morning meditation sessions, I must create conditions in which the mind is operating at its highest potential for maximal clarity and power of concentration in every session. So if I'm completely honest with myself and with my commitment to this Path, I have to confess that the reasons for giving up drinking clearly outweigh those of not doing it (not even mentioning the arguments about kamma and what Buddha himself said, as discussed on earlier posts).
Nevertheless, I must confess that I am hesitant to give up drinking forever, since the social challenges appear daunting (eg at a friend's wedding or bachelor party). On the other hand, something tells me that dealing with those challenges will present a number of useful insights in its own right (eg about the ego, about attachment to the opinions of others, about the nature of my friendships, etc).
"I do not perceive even one other thing, o monks, that when developed and cultivated entails such great happiness as the mind" (AN 1.10, transl. Ven. Bikkhu Bodhi)