The whole thing is awesome; here are parts that specifically caught my attention:
Recording attendance. Especially when the topic is announced in advance, this helps collect data about how many people are really interested in the topic. (For example, people may approve of some idea in far mode, but then decide they have a better way to spend their time.) Of course, attendance is strongly confounded with things unrelated to the meetup, such as summer holidays.
Yes, the icebreakers for the new people. (But also for the old people who e.g. forgot someone's name.)
If people finding out about meetups on sources other than LW and SSC have confused ideas about rationality, perhaps make a FAQ specifically targeted at them? And include it in all announcements outside LW/SSC.
Group Debugging - I am stealing this immediately!
"What's something that's worth about as much to you as one of your pinky fingers?" - that's a simple and effective way to measure values.
Oh yeah, I forgot to suggest doing rounds of names during the introductory period of the meetup. That's helpful too. (A benefit of being the organizer is it's much easier to remember everyone's name, because if you have a bunch of regulars, you only have to remember one or two new names each week.)
I'm skeptical of making an FAQ for new people, unless it's genuinely made up of questions that you, personally, have received in this circumstance. Seems likely to come off as condescending.
My strategy with people who seem like they come from very far outside the LW subculture is to try to meet them where they are... ask questions like "what did you find interesting about rationality / why did you come here?" and try to meet them in the middle, or have a productive conversation if you have obvious disagreements. Focus on areas where you have commonalities, rather than telling them everything they are wrong about right off the bat.
But I don't get too much practice with this, since most of our new people find the meetups through the LW website.
It seems like explicitly reading / deep questions / object level rationality content style meetups are about 30% of your schedule? Do you think that's about right? How much would you estimate people just spontaneously talk amongst themselves about "inside baseball" topics.
Nope, that is not right.
Our schedule is weighted towards doing things that are simpler and have good replay value. We do board games and projects each once every 5 weeks, Group Debugging a little less often than that, and mix the remaining meetups in semi-arbitrarily, at a frequency of once every couple months for each type.
We do almost no explicit rationality content at all. Only reading discussion meetups could be described as that, and we do them very rarely.
People talk amongst themselves about whatever they want. Usually the structured portion of the meetup is about 1/3 of the total time, and the rest is just general conversation. There's a fair amount of it that ends up being related to rationality inside baseball, but it depends on who shows up and what they're thinking about on a given week.
My spouse and I have been running LessWrong meetups in two different cities for the past six years. Over time, we've gotten lazier and lazier about organizing, while still maintaining similar results, mostly by coming up with a bunch of simple recipes and scripts for running meetups. Here I have documented how we do it in excruciating detail, so others can use what we do.