Seventies heroes Chicago rock uptown for a nostalgia-soaked celebration of warmer, friendlier times. Which is not to say there are no surprises in store: Expect a rendition of "If You Leave Me Now" by a high-bidding audience member (with proceeds benefiting the American Cancer Society), a guest appearance by American Idol alum Constantine Maroulis, and an opening act that plays Chicago's greatest hits as Latin-style mambo, cha-cha and merengue burners. (Every word of this is true.)
