Originally Posted by mcbrown
As someone who has hosted these types of dinners with candidates more times than I can count, I can say definitively that I don't remember a single thing about what anyone was wearing and that it had absolutely no bearing on the hiring decision. A suit (with tie) is always fine at any firm other than possibly a few creative or tech companies. But if the invitation says business casual then business casual is also fine. If it were me I would wear a suit, but only because I think that I would feel more professional and confident in a suit and perhaps project myself accordingly. If wearing a suit made me feel uncomfortable and self-conscious, or if I had an ill-fitting suit and bad ties but great casual clothes, I would wear business casual.
There's nothing to game here other than your own feelings. So wear whatever makes you feel best about yourself and you will be fine.
This is SF where if you can't see the hand picking on the lapel of some kid just out of college, he doesn't bring the SAB briefcase, and his tie dimple isn't perfectly rakishly off center, then he is obviously not serious about getting job.