I’m really enjoying looking at these challenge entries!
I especially like Ahqi’s Studio Ghibli style one and the Deep Dream ones (especially korabkoff’s.)
gerardo’s tests look terrific, especially the 3rd of the smaller close-up ones. That shows a nice fill-level that would be good to spread into the sun-lit parts of the scene (the cracks/corners/blacks shouldn’t go any darker on the sunny side of the street than they do on the shady side.)
Actually, to everybody, I think this is one of those scenes that you could light fill-light first, just getting a nice base illumination via IBL (or fill lights plus some occlusion, whatever your approach) to make sure blacks don’t go too black, and try to get appropriate reflections on things that might be reflective (even if a metal lamppost is painted black and you don’t see reflections on the parts facing towards camera, you’d at least expect some reflections around the edges.) After that some atmosphere (it doesn’t have to be foggy, but some kind of sense of depth to make sure what’s far away doesn’t look too similar to what’s up close) would help – maybe you can do a lot of that in post if you’ve rendered out some depth information. Anyway, if you get the fills, reflections, and depth fading done, then adding specific light sources like sun, moon, lamps, lit windows, or whatever could be your last step after the foundation is built. Just my 2 cents.