Saw it in a one screen theater in our town that's been gone for about 25 years. I remember CRYING my eyes out when it all came crashing down, and even worse when he went home.
Then I'd have to say Raiders with my dad. Saw it 9 times on screen. He still talks about how excited I was. It's one of his favorite memories. Then it was my brother getting me out of school early with some kind of bogus excuse to go see the latest Trek movie. I remember getting called out of class and being told I had a dentist appointment, and I was like "huh?", then when I got out my brother took me to see The Search for Spock.
OK...I'm officially quite sad and nostalgic now...thx Bossk. :-)