American Literature: The best Sinclair Lewis Novel and why?

"His name was George F Babbit and he was very nimble at selling houses to people for more than they could afford to pay."

I've never forgotten the opening sentence of a book that gives a most remarkable and chilling look into the mind of a man. Not an evil man but one too weak willed to stand up to the deep- seated rightist viewpoint of his society. A man who chooses to collude and gets sucked in for gain.