I believe that one should act consistently on their principles, even and especially in front of their children. If you are ashamed of drinking, then you should stop, period. If you are not ashamed of drinking (or smoking, or whatever) and consider it to be an acceptable vice that brings you greater pleasure than the costs, then you should not be afraid to do it in front of your children. This openness allows you to explain your reasoning and your choices, and provides a stronger parental example then "sneaking around" doing something "bad". What will they think if they catch you? What can you say? By so doing you are demonstrating that it's okay to have a disconnect between your principles and actions.