I have never experienced talking to a stranger at a bar - one goes with ones friends, and gets to know them better, but nobody known to nobody ever gets added to the conversation.

I've been in bars all over the world, ranging from Tokyo to NYC to SF to now Seattle - with plenty of other cities in between.

If you'll pardon my french here: the PNW is the most clique-filled bar experience I have experienced worldwide and it's really very boring to deal with. You can make it work, but it winds up being more work than is ideal.