Make all the textures as sort of a light gray and white, like a huge galactic city would have. Then use colored lighting to tint them, it'll look better. Like for a blueish sunrise you might want RGB light as (0, 0, 50)... Just something really small on the blue like 50 for a tint. Or maybe like 50 blue 20 green so it appears less purple. Maybe for a sunset do like 100 red, 50 green, 20 blue, I dunno, fool with them till you get a very slight blue/purple color.
What's really great about this method is that the outsides of all your buildings will be tinted from the sky, and the inside will be non-colored!
Clarionet, n. An instrument of torture operated by a person with cotton in his ears. There are two instruments that are worse than a clarionet -- two clarionets.