OK, so... from left to right, we have:
The Doral, by Reinheimer and Associates (1982)
One Prudential Plaza by Naess & Murphy (1955)
Two Prudential Plaza by Loebl, Schlossman & Hackl (1990)Standard Oil Building (now Aon Centre) by Edward Durell Stone and Perkins & Will (1970) Aqua by Studio Gang (2007)
Blue Cross-Blue Shield Building by Goetsch Partners and Lohan Assocates (1995)
Oh, and I think the Pritzker Pavilion in the foreground is by somebody, too, but I can't remember his name...