"Now, you listen to me! I don't want any plastics, and I don't want any ground-floors, and I don't want to get married - ever - to anyone! You understand that? I want to do what I want to do. And you're... and you're... Oh, Mary, Mary... Would you?... Would you?..."
"Just a minute - just a minute. Now, hold on, Mr. Potter. You're right when you say my father was no businessman. I know that. Why he ever started this cheap, penny-ante Building and Loan, I'll never know. But neither you nor anyone else can say anything against his character, because his whole life was… Why, in the twenty-five years since he and Uncle Billy started this thing, he never once thought of himself. Isn't that right, Uncle Billy? He didn't save enough money to send Harry to school, let alone me. But he did help a few people get out of your slums, Mr. Potter, and what's wrong with that? […] You, you said – what'd you say a minute ago? They had to wait and save their money before they even ought to think of a decent home. Wait? Wait for what? Until their children grow up and leave them? Until they're so old and broken down that they... Do you know how long it takes a working man to save five thousand dollars? Just remember this, Mr. Potter, that this rabble you're talking about – they do most of the working and paying and living and dying in this community. Well, is it too much to have them work and pay and live and die in a couple of decent rooms and a bath? Anyway, my father didn't think so. People were human beings to him. But to you, a warped, frustrated old man, they're cattle. Well, in my book he died a much richer man than you'll ever be."
"Merry Christmas, Bedford Falls! Merry Christmas, movie house! Merry Christmas, Emporium! Merry Christmas, you wonderful old Building and Loan!"
EDIT: Go here for an excellent article by James Zborowski on some of the joys and complexities of It's a Wonderful Life.