I personally refused to put myself in situations where I might be tempted to drink for about 2 months until I felt that I was strong enough to say no. As boring as this might be, I had to put my sobriety before fun and friends to make sure that I was ok.
Instead of being tempted to go out, I would make plans for myself early the next morning and because I had obligations, I would use that as an excuse to stay home if necessary.
At 21 days sober I'm not sure that it's a good idea to be going to places where they have an open bar. Think about the potential threat to your sobriety with every choice you make as far as going out BEFORE hand, and if you think there's a chance you may drink, simply don't go. Stay home, go to the gym, see a movie.