forgive me, but scott joplin comes to mind. not sure which rag. will listen to a few tonight.
or, some kind of music or combo from the soundtrack to 'sleepless in seattle.'
i think 'melancholy blues' suddenly switching to 'happy train' would also work. u know. some soul music.
or some beegees music like 'all by myself ' and suddenly switch to some kind of happy song like 'happy ever after.'