I'm not sure that registering and having enclosed spaces is the best way to make women feel welcome. I'm sure that might make some women feel that way, but at the Wiknic we had in LA, for example, far more women who had never edited and not signed up for the event just dropped by because we were in a park and looked inviting. Yes, Wikipedians can look inviting! (I don't think it hurt that there were other women there, either.) I think there is room for both approaches.