What an agonizing choice! I immediately thought "It's a world of laughter, a world of tears, It's a world of hopes and a world of fears . . ." But then, I would really "like to join our jamboree, there's a simple rule that's compulsory, mortals pay a token fee, rest in peace, the haunting's free, so hurry back we would like your company!" But, there are times when I just can't stop singing about the "great big beautiful tomorrow."
Ack! Disney music overload! I'll pick one. I don't know which yet.
Edit: Grim Grinning Ghosts won for me.