My BF and I are coming to San Fran for the long weekend and are looking for suggestions for a place to meet up with local friends on Saturday night. We both have a lot of friends in the area that have different schedules and obligations for the weekend. So, what we're looking for is a place where we can just tell people we'll be and our friends can come and get food and/or drink whenever convenient for them, but not feel required to order a full meal. Also, a place where we can show up at 6pm and hang out until 10 or later and not feel like we've taken over a place. Essentially, we're looking for somewhere we can have an open house type of deal. Neighborhood-wise, the Castro, Mission, or Downtown would be ideal.