In the entire history of the Academy Awards, only six Best Picture winners have been 100 minutes or less. It seems that traditional, Oscar-bait "prestige" pictures tend to run long, attracting Academy voters with their sheer volume. Extra-long films are also a little rare, though, as only five Best Picture Winners are 200 minutes or more. Additionally, a whopping 18 Best Pictures have been between 160 and 195 minutes, so voters clearly don't mind longer movies. Indeed, the average length of a Best Picture winner is 136 minutes. In terms of cinematic storytelling, that seems to be the sweet spot. 

Of course, Roger Ebert's adage needs to be mentioned. The famed critics once posited that no good movie is too long, and no bad movie is short enough. The actual length of a film doesn't really matter, so long as it's a quality picture, and it makes good use of its time. Personally, I feel...