I'm a moderator at Writers.SE. It's an interesting beta-site in many ways; the other mods and I are always putting a lot of thought into what needs attention and what can help us move forward. We've always got lots to hash out - we've got site definition issues, quality issues, promotion issues, what have you.
Many of our discussions go beyond our specific site. Some ideas for promotion would carry easily to other sites; site-definition issues are not dissimilar between different sites; etc., etc. I think that many discussions we've been holding among the mods, or on our meta, would greatly benefit from being shared among a wider community - that of people interested in nurturing and promoting SE beta sites.
The most appropriate place I've found for such discussions is Meta.SO, and indeed I've raised several such issues here. While response has been overall quite positive, I don't feel I got the reaction or scope of discussion that I'd expect. I expected to see more responses and insights from other people working hard on their own beta sites; I don't think I've gotten much of that. I'm concerned that on Meta.SO, this type of question gets lost - mods in disparate communities don't necessarily follow SO's Meta.
Other conceivable alternatives are the Area 51 discussion area (but discussion there seems highly focused on individual proposals, not on general treatment of what comes after launching the beta), and the mod-only Teachers' Lounge (chat room, and so obviously limited in its utility as a substitute for Meta).
Where is the most appropriate place for discussions about maintaining, nurturing, and promoting beta sites? Can we make our existing options more successful?