Something Art Deco like would be the best choice. Really bright and somehow in a constant dawn/dusk.
I think Snyder would do it CGI completely, but then again Nolan is on board too, who as we all know does most things without. What is the most Art Deco-ish city in the U.S.?
And I never ever want to see Superman flying around the Statue of Liberty again.
Damn I always hated this. The statue is far too recognizable as being part of New York City. And Metropolis is not NYC.
Something like that might work in GTA4, but not as a living and breathing Metropolis.