I ended up using a color-inverted version of a Morris cityscape, and stretched it across the five volumes, which turned out nice. For each individual volume, I used a detail of the original Morris cover art, encapsulated within a restrained deco frame, on top of a mostly black field, with a screened-back detail of the same cover art. In contrast to the imagery, the type is humble with a touch of history.
I'm pretty happy with the results.