The scene aboard the helicopter

When George and Lucy are aboard the helicopter and discussing the beauty of the city and particularly how William Van Alen's vision of the Chrysler Building came to pass.

Lucy: "It's is pretty amazing what dreams and lots of money can do, isn't it?"
George: "Yes, it is."
Lucy: "And you know you're part of that George."
George: "Yes, I am."
Lucy: "All you have to do is use your power for good instead of evil."
George: "If only I would."

On the surface this discussion may appear as sentimental bantering, but I find it to be the heart and soul of the relationship between Lucy and George, and what makes this film so endearing. The ability of a good person to steer a friend who has good intentions within him in the right direction.