Ask everyone to sign up for different methods of communication. Pick a method for managing the lists. Avoid the additional publicity public facebook postings get you when someone likes it.
Those are real tradeoffs that many groups aren't willing to accept, regardless of how willing a single person is to shoulder the burden.
Ask everyone to sign up for different methods of communication
That's exactly what you are doing by insisting on Facebook use unnecessarily, when email is the true common denominator (doesn't everyone in your friends list have email?).
Nearly everyone is already there, and the number that isn't continues to fall every year. Yes everyone already has email, but list management and group organization is much worse. Even compared to Google groups.
Those are real tradeoffs that many groups aren't willing to accept, regardless of how willing a single person is to shoulder the burden.