Jon Hamm should be Superman.
He has the chiseled face that people seem to want to see, he is a very good actor, and also pulls off the trenchcoat/hat Clark Kent look very well (haven't seen him with glasses though). He really seems to have the look of the alex ross superman.
Alas, WB probably wants someone younger to make a franchise with. Of course that kind of thinking got us the really uninspiring Kate Bosworth and Routh.