World Trade Center: The scene when the Marine finds Jimeno and McLaughlin (however his last name is spelled), and he says "you are our mission". I just always cry, like happy tears. Even though you know they are okay, it's like 'yeah'.
United 93: basically cried through the entire movie.
Pearl Harbor: When Danny dies and Rafe tells him he's going to be dad. I'm like "tears"
Superman Returns: The end when Clark is saying the whole "the father is the son is the father" thing to his son. Again "tears".