Lovely scene so far, but ur AO is killing most of your values cause the contrast is so drastic; agreeing with what lobo said, i also thot it was a toon shader you had going on. If you manage to soften them up it'll do a lot good for the scene.
You were having those color blotches due to the static level lighting scale being set to 1 and your scene being larger than gears of war. Yea it doesn't make much sense. It's even what the tool tip reads in the world lightmass settings. You could have set the static level lighting scale higher or scale down your level,…