Here is a render of a test background, that I've been working on for a while for my film:
I like using Maya to plot out a background, as it feels like I'm building something in three dimensions. It helps me to get a better feel of the world I'm building.
This is just a rough version blocking in the main architecture - for the city scenes, I decided to go for a Art Deco design, as it works really well in CG.
I overlayed a few textures over it, to get the feel I want for the finished film ~ a sepia-toned city.