If ordering a martini at dinner keeps them from hiring you, then I don't see that as the kind of place you truly want to work. That's how I tend to think about these things, anyway.
This is really what it comes down to.
Also, don't feel like you absolutely have to order a drink if you typically don't drink at all. I worked with a couple of people who don't drink for personal/religious reasons, and no one ever said anything at all. They all got offers. It wasn't a big deal. As I said before, as long as you stick to one drink at dinner, no one will really care. I just suggested sticking with beer/wine if that's what the others were doing just to make sure you didn't stress over anything next time. (OCI and interviewing is terrible if for no other reason than you likely put yourself under a far more exacting microscope than any of these attorneys and interviewers ever do)
microscope - totally true. the dinner was just awkward -- i didn't feel like i "connected" with the people as much as i did with the interviewers the next day. i think i was also visibly nervous at first (hand shaking when picked up drink, spilled a little bit), but it got better through the evening. like i said, i only drank half of it, so hopefully that tilted the situation in my favor if it was even bad to begin with.
you're right, i should just do things i'm comfortable with. if nothing else, i know what not to do next time. i'll let you know what i hear from this firm.