I'm in complete agreement with James at the Wizards' book club. Naming just one favorite movie can cause a massive hole in your brain.
Even more frightening: looking at the long list provided by other authors (who mostly cheated and named more than one), I only found a single title that I had not seen. The Russian Stalker named by Athans. And I'm googling it right now to see if I can get a copy.
Nobody asked about my favorite places to watch movies and that's a shame. Because there are still so many great old theaters left in Seattle. I am a regular visitor to the Harvard Exit (wonderful balcony and a ghost), the Egyptian (best espresso in a cinema), the Uptown (close to many great restaurants and now two used bookstores!), the Admiral (West Seattle's favorite discount house), and more. Ballard's Bay is one of my favorite place for family films. Last winter, I was there for Where the Wild Things Are, a movie that still haunts me.
If you are a movie buff and live in Seattle, there's always something beyond the latest blockbuster to see. Our Northwest Film Forum, our year-round theater for the Seattle International Film Festival, various community houses and events (friends keep raving about Central Cinema although I haven't made any of their shows yet), and more.
We even have a regular showings of silent films in the very grand gold-and-white Paramount Theatre, complete with live musical accompaniment on the Mighty Wurlitzer Organ (one of only three working movie house organs from the silent era). The theme this spring is the South Seas.