Well, hopefully I can take up a little of the modelling shortfall, I'm comfortable with max but have very little experience with exporting assets to a game engine/editor. No doubt google, salvatoris and these forums will smooth over anything that crops up, though.
Temphage, as I see it there are 3 heights of buildings that really matter, ones you can see and shoot over, ones you can't but can jump onto, like the concrete hangers on the marshes airfield and ones too high to jump onto. An interesting mix of those 3 seeems like it would be the key, along with varying widths and lengths of streets and some open spaces, throw in some landmarks and we're set, right?
Ghiest, thanks for the quick research! There really is a bit of everything, isn't there, even the world trade centre

There's star wars to 18th century masonry to 1980s futurism, to 40k-esque gothic/military/industrial and more, so basically, anything goes. Hey, I'm back to where I started - ace.
Anyway, I'll crack on with what I have tomorrow, as it's gone 2am here. If anyone can think of a particular city, culture, planet etc. that has a distinct and consistent theme in the canon, and would perhaps be visually recognisable to other fans please let me know, anything to get a handle on would help. Cheers