Being involved entirely as a spectator, the massed approach was one of my most memorable aviation moments. The first time I saw it (1991, I think), the aircraft rose up from behind the horizon in front of the crowd one by one, working out from the centre towards both ends of the line. Naturally your eyes will follow the line one way, and when the last helicopter in line rises up, you suddenly realise that the same thing was happening at the other end. Spectacular.
The flypast at the start of Culdrose air day used to be impressive as well. I'm sure that there used to be two diamond nine formations of Gazelles as well as one of Sea Kings back in the 1990s.