The lord of the rings trilogy
One of the only trilogies that feels like a single, coherent epic film. You will commit a full weekend and you will not regret it. But for heaven sake don't forget to pause the movie to say that Viggo Mortensen actually broke his foot kicking the helmet! The gold standard of "we are doing this all weekend." There is no casual watch - you commit, and it commits back harder.
3 films

A hobbit leaves home and immediately regrets it. Nine strangers become a family, then immediately stop being a family. The longest setup in cinema history and you will not notice.
Official synopsis
Young hobbit Frodo Baggins, after inheriting a mysterious ring from his uncle Bilbo, must leave his home in order to keep it from falling into the hands of its evil creator. Along the way, a fellowship is formed to protect the ringbearer and make sure that the ring arrives at its final destination: Mt. Doom, the only place where it can be destroyed.

