In Scolforo v Corbett, a reporter sued and won the right to access the official calendar of the sitting Governor of Pennsylvania, Gov. Tom Corbett.
In response, lawyers for the governor are advising staff to regularly purge their calendars of personal information.
Laws vary state by state, but in many circumstances there are routine FOIA exemptions for "items of a personal nature" (Michigan (1)(a)); that should result in any request for a calendar being redactable after the fact. You might always wonder whether someone purging items from their calendar after the meetings have happened would get a bit overzealous in the effort.