Slate's Gabfests would probably be a good model for these. They're really entertaining to listen to, and very insightful. They've never discussed it explicitly

Slate's Gabfests would probably be a good model for these. They're really entertaining to listen to, and very insightful. They've never discussed it explicitly, but their "formula" seems to include: - usually at most three main topics (occasionally more) - a closing bit of silliness - they make sure everyone has had time to prepare something to say on the topics to-be-discussed - each person has a computer handy (but I never hear anyone typing, which is nice) - they have some facility for including external audio (for discussion, e.g., music or ads) - one person leads the discussion, trying to keep people on topic, and making sure that a transition happens to the next one at the right time - keep the podcast between 45 and 60 minutes, fairly consistently - they release it at a regular time - it's weekly, and comes out at a regular time