- Star Wars (original trilogy
- (contentiously!) Lord of the Rings
- Spider-Man trilogy
- The Godfather trilogy
- Alien 1-3
- The Dark Knight trilogy
Usually people will say their favourite part of a story is the ending, which is natural - the denouement is where characters typically achieve some sort of positive resolution.
Why then do many trilogies excel at putting characters through the wringer in the first and second acts, only to fluff it at the finish line? Who would say the last film in any of these trilogies was the best?
In the case of Return of the Jedi, it is clear that George Lucas lost his nerve and abandoned the originally proposed, darker resolution. Return of the King seemed to not want to end at all and was generally rather pleased with itself (I must admit, I checked out when the green ghost army appeared).
The failures of Spider-Man 3 and Alien 3 are largely due to their respective directors' visions becoming compromised by studio meddling (after the successes of earlier instalments).
The Godfather part III smacks of unnecessary-sequel-itis, because it's just so tempting to want to make two great movies into the holy grail 'perfect trilogy'.
As for The Dark Knight Rises, I actually think it is under-appreciated, while Batman Begins and especially The Dark Knight are held in too high esteem.
Or perhaps it Is human nature that we are inherently unsatisfied by happy-ever-afters. It is the struggle itself that we find most compelling, and it draws us back again and again. Maybe we have a primal urge to see challenges overcome; happy endings we can figure out for ourselves.