"For a couple of hours out of the whole year, we are the people we always hoped we would be."
Everyone, even the three ghosts (plus Herman and Lew) celebrating near the end of the movie. Even the ghouls inside the Ghost of Christmas Future's robes can be seen partying with the rest, happily singing and enjoying Christmas candies no less.
When Frank berates Herman for dying because he should have stayed at Operation Reachout. Also counts one of the films biggest tearjerkers.
Also because it partly counts as him beginning to realize that his own life sucks without Claire and the speech is just as relevant to him. The Ghost of Christmas Future drives the point home, but the seeds are sown right there.
Frank: You moron! You jerk! You should have stayed at Clair's! She would have taken care of you!