I had this same setting concept years and years ago and started implementing it in Megazeux. Only I called it "the Complex" and it was a Blade Runner type of dystopia where people got into lots of gunfights for shallow, petty reasons. I didn't finish it.
The body of work that originally hooked me on the Megastructure concept is the
Blame! manga series by Tsutomu Nihei. I think we resonate with the idea easily, like many other staples of sci-fi. I see it as being more enclosed than Blade Runner, but the atmosphere is very similar.
I'd be interested in hearing more about your strategy for generating the landscapes.
I didn't have a procedural strategy, I was just drawing out map data by hand - game flow was more important to me at the time than the technical aspect of "representing a really huge setting." I made it to about three rooms of content before stopping.
If I were doing it today I'd probably start with a voxel array that generally describes different sections of the structure and their purpose/parameters, and then everything would be connected and detailed algorithmically. So the data would still be hand-tuned. If I then got it to the point where I wanted to make it truly infinite, I would create a high-level algorithm that replicates the thought process I used to make the original data set. If I wanted more variant detail at the low level, I would do a similar thing there by hand-editing the architecture, specific items, etc., and then reproducing my process.
Essentially it boils down to: Create a good dataset by hand. Figure out how to make more of it. Repeat across all levels of data. I've learned(by failing at it) that you can't just have the computer barf out some noise and expect it to hold long-term interest - intent, structure, and relationships are important.