One of my favorite movies has to be The Princess Bride. This movie will always be a classic to me. I've watched it so many times, I can practically quote the whole thing right along with the actors. Not only do I have the movie, but I also have the soundtrack, which is excellent background music for writing fantasy. Fantastic!
This story within a story begins with a boy who is home sick. His grandfather visits, bringing his favorite book. With the promise of "fencing, fighting, torture, revenge, giants, monsters, chases, escapes, true love, miracles," the grandson agrees to listen to the story.
Buttercup falls in love with a poor farmboy. Before he leaves to seek his fortune, he promises that he will always come for her. "Because this is true love. Do you think this happens everyday?" When she hears he has been murdered by the Dread Pirate Roberts, she is devastated. Prince Humperdink chooses her to become his princess though she does not love him. Then she is kidnapped by a trio of odd characters and followed by the Man in Black.
Swordfights, vows, and hilarity ensues. I hope this movie remains a part of popular culture for a long time. With so many quotable lines and references which have slipped into common parlance, I find it "inconceivable" to imagine this story ever being forgotten completely.