Okay, I totally mis-understood this thread title. I thought this was about highly rated films, not just by the viewers, but by everyone including film-makers.
So when most film-makers vote Citizen Kane as being the best film or The Godfather, they're saying not only because it was 'exciting' but because it broke ground on technique, some new device or storytelling. So, I find parts of 2001 'boring' but I also recognise why it's so highly rated (heck, it still looks better than a lot of today's space films).