Alright, describe the city for me.  Are you thinking somewhere generic in a specified nation?  Or somewhere unique that's more of a crossroads for nations?  Is it an older, conservative city?  Is it newer, younger, with more liberal views?  What is the approximate climate?  The current time of year?

Is this a university town?  Touristy?  Do most of the people have generational ties to the city, or is it newer and growing quickly as people move to it from elsewhere?  What industry (or industries) is bringing in the majority of people?  Is it technology, with the heavy need for tech-savvy, university-educated individuals?  That would make for an upper-middleclass population, generally speaking.  Maybe it's an industrial zone, lots of smog and warehouses, and the company happened to find a comfortable place to set up?

Please and thanks.  I admit, I'm not sure how many of these questions are going to prove relevant; it's more just... I'm trying to picture the world these characters are in.  How they have grown up, who their ancestors are, what they see as they look to the future--all of that.