If I had only one day in the Spring, Summer or Fall, my number one thing is an architecture cruise on the Chicago River. If I had only one day in the Winter, I'd skip the Willis/Sears tower and make my number one thing a visit North Michigan Avenue. If you walk from the river north to the John Hancock Tower, you'll enjoy one of Chicago's signature experiences. In my opinion, the John Hancock tower is a more beautiful example of modern skyscrapers than the Sears tower. And you get better views of the lake from the observation deck. But if you want to look 1000 feet straight down from the top of a skyscrpater, then you have to go to the Willis/Sears Tower SkyDeck.
