I love when musical films use the songs as leitmotifs in the score. A great example of this is Mary Poppins. Irwin Kostal did a great job making motifs for all the Sherman Brothers' songs like using "A British Bank" for Mr. Banks himself. In fact, he took a deleted song for Admiral Boom and used it as his motif in the score anyway.
Can you think of other great examples, be they by the original composers of the songs or others?
mayorodoyle t1_ja89mwg wrote
Not sure if this counts but "Man Of Constant Sorrow" in O Brother Where Art Thou?