Films you have never seen that everyone thinks you should see.

1. Braveheart- feel the most shame about this one.
2. Jaws- much less shame over this one.
3. Titantic- I consider never seeing a badge of honor.
4. Avatar- tried watching a few times. Bored me to tears. Nothing about it grabs me.

As for the OP's list, as others have said, Godfather 1 and 2 are must watch. Just pretend 3 doesn't exist.