Here's my initial thumbnail doodle for the cover. I even drew in a first stab at the typography, just to get some sense of how that might work (or not). I knew I was only responsible for the cover art, but I factor in the type placement when I sketch thumbnails for covers. Sometimes I draw it in, even if I'm not designing the final type, and sometimes I just leave space for it. It's always a consideration though. The final type design is by Argh! Nottingham (see below), and I dig it. It's a simple, strong solution, and says "noir" without being cliche.
As for the art, I was given a solid brief from Angry Robot that described what they wanted on the cover. They wanted three main characters, and their pets, to be the focus, and offered a fairly specific way to handle it. I saw the cover a completely different way, but made sure to include all of the elements (main characters, pets, setting, mood, attitude). They were terrific and said "go for it!"
Relevant note here -- it's not often that authors have input during the process of making a cover. There are lots of reasons for this, and that could be a whole blog post by itself. The point is it doesn't happen often. In this case, Lauren was very involved, and she and Marc Gascoigne (publishing director) were fun collaborators. It was my first time working with Angry Robot, and a pleasure. They're building a terrific line of books. I'm really excited about ZOO CITY, and am already looking forward to its release in May.