On a perfect summer night, my wife and I and a bunch of friends saw Elton John and Billy Joel in concert at Wrigley Field. They played for over 3.5 hours, alternating between singing solos, singing duets and singing each others' hits. Both Elton and Billy were enthusiastic performers, but Billy appeared a little more energetic. To add a local touch to the show, Elton John played a few lines from "Take Me Out to the Ballgame" and...