I'm getting ready to start an Urban Fantasy styled campaign set in the near future and wanted someplace that seemed real but also had a creepy not real feel to it. I ended up inventing a city rather than adapting one of the real cities in the US.
Influences: I wanted the feel of Gotham which led me to using Nolan's map for inspiration. The actual design of the city is inspired by New York, Chicago, Kowloon, Hudson City [Hero Games], and, of course, Gotham City. The Oldtown section is where I intend to start the action so it is getting the most love right now.
Tools: Illustrator CS 2
Here is where I've gotten so far.