We started with the 2018 Meetups Everywhere with a showing of 12 people. We've gained and lost some over time and currently have a rotation of about 15-20 regulars, of which anywhere from 4 to 7 might come on a typical meetup. Topics range wildly and on a given day we might talk about ACX material 50% of the time or not at all.
We usually meet at the Common House at Rocky Hill Cohousing (where one of our members lives), and occasionally when it isn't available we fall back to several bars and restaurants in Northampton, most often Packard's.
Needless to say, rationalists and EA folks of all stripes are welcome, including total newcomers. We've had people ranging from old-school rationalists dating back before Less Wrong, to people who just heard about rationalism the same day, to a literal baby (who, frankly, didn't really pull his weight in the conversation).
Look forward to seeing you!