I think it would nice to have options at event creation/edit event, that allow the owner/event admin to set the event to "Public", "Public - Request entry/invite only" and "Private - invite only". "Public" - Anyone can view and RSVP. "Public - Request entry/Invite only" - Anyone can view the event, but they will either have to request attendance or be invited by event owner/admin. "Private - invite only" - No one can view the event apart from event owner/admin and attendants. All attendants must be invited.