I had a beer in bar where Al Franken was present, though I don't remember if he had a beer. Senate candidate Bob Casey was in a bar in my presence while I was having a beer, though I don't remember if he had one.
I think there's only one member of Congress that I've really "had a beer with" in the sense of it not being in any way a campaign type event. I'll protect his reputation and not tell you who it was.