There are a few I LOVE to watch over and over again.
Serenity - it's intense, but funny too. I probably watch it two or three times a year.
Signs - OMG, I LOVE this movie! I watch it probably 3 or 4 times a year.
Lord of the Rings trilogy - I love it so much, who can count LOL!
Practical Magic - I always make sure to watch this at least during the fall, but usually end up getting to watch it at least twice throughout the year.