Every month pick a famous person and a few representative articles/books. On their birthday, meet up and discuss. Similar questions as a Junto, evaluating their life. Scientists, artists, musicians, etc. all work. My nominations: Charles Darwin. Something like this already exists for Robbie Burns. I've always wanted to celebrate Iain Banks this way.
Every month someone comes up with a new game with rules. Everyone comes and plays it. I believe there is already a group like this in nyc.
I have done one of these and it is interesting. Feels a bit out of time, but nice to talk about virtue and improvement in a strongly positive sum way.
Every month, there is an auction, paid in "points", for who controls the meetup. Every time you attend you gain one point. Whoever wins the auction decides what will be done that month. This comes from newer board games which use something like this for job allocation.