I would definitely vouch for NYC. We live within commuting distance of it, and when we're feeling like being around a bigger group of poly people, we head to NYC. There is a great group there - Open Love NY (http://openloveny.com/). They do poly cocktails once a month and every week, there is a different discussion group. Sometimes they get authors of polybooks, or people who run poly workshops/people who have a lot of "poly cred" to give talks/guide exercises/etc.
I've been to both the cocktails thing once or twice as well as a few discussion groups over the past few years, and both were really nice and welcoming.
I've been to both the cocktails thing once or twice as well as a few discussion groups over the past few years, and both were really nice and welcoming.