One film that uses narration in order to move the story line is Fight Club. I believe that the director decided to use narration because it makes the aduience connect on a deeper level with the protagonist as we can hear his thoughts which is something very personal. The audeinces gets a better understanding to how and why he does what he does.
I think that it also used narration because the story was initially a book so by using narration it gives the audience a sense of nastagia of reading the book again.
Lastly his character uses voice-over narration throughout to convey the journey of his involvement with Tyler Durden, leader of the Fight Club.