Awesome flickr, man!
This looks great, although too dark (except for the most recent image), and I love your procedural architecture renders as well. The former render geek in me is drooling.
I agree, you need to find a sound designer to partner with that has a taste as sophisticated as yours. Knowing the right direction to go should become a lot more clear once you find that partner and get some sound in there.
In terms of direction, I'd highly suggest you think about what it means to evoke a sense of
being. What does it mean to be in that space? You'll want the sound to reflect that, as well as some parts of the world that make it feel alive (in the general sense of the word, I realize yours is highly synthetic).
Another suggestion would be to listen to what the design is "telling you." I know that's highly philosophical, but given your level of craftsmanship, it doesn't seem very fruitful to give super practical advice, heh.
Hmm...here's something more practical:
How can you apply the idea of procedural architecture to the experience itself? One thing I've experimented with is narrative elements that are mixed procedurally to understand how meaning comes about due to pieces that are adjacent to each other, just like in your renders. Maybe you could do that here.
Or make the fact that this world consists of procedural architecture part of the story. An idea I've had for a short videogame included having a terrain that repeats, which many players would just accept as a necessary evil to create more content. But in this case it is actually part of the fictional world. The character inside the world sees all the sudden that the environment is repeating and that clues him into the fact that something is wrong. You don't have to do that exactly, but maybe the construction of the architecture could play into the fiction of the world like that.
