"Our Children" from the musical "Ragtime" - Lynn Ahrens and Stephen Flaherty

Ragtime is a fantastic musical about the turmoil of the early 20th Century, with a fantastic variety of moving ballads and fun patter songs.  The second act is quite a bit darker than the first act, but still has great music, including this song, "Our Children," where the wealthy widow and immigrant widower are watching their two children play.  Check out the Wikipedia page for more about this great musical.