I think there is actual surveillance of the last 'official' commission meeting in '85. If I remember correctly it took place in Staten Island; the feds trailed Castellano there and have pictures of him coming and going.

in 'king of the godfathers' they describe (on account of Vitale) what the last mini-meeting in 2000 was like. Sounded like a lot of arguing and basically a pointless meeting. There really is no reason for the families' administrations to all gather in one place these days