Well, usually vampire ceremonies are, in Camarilla cases, for show, grandeur, exposition and glory/pomp. Sabbat ones are communal and basically listed as Auctoritas Ritae or Ignoblis Ritae, so it's pretty straightforward. Anarchs probably simulate humans if they do something ceremonial, but usually I imagine they just have parties, social or political reunions, war councils and informational gatherings.
Most illustrious Camarilla Kindred ceremonies date back from at least Middle Ages (there is a Dark Ages book, High Clans I think, that touches upon it).
There is ceremonies for the...