After I created my physical sky, I deleted the mia_exposure_simple and used a mia_exposure_photographic on the camera instead.
All shaders are mia_materials with gamma correct nodes (with a gamma of .455) plugged into all the color slots (diffuse, refraction color, etc) and AO checked on. Plugged a cloud texture into the bump and resized the 3dTexture a little bit and took the bump depth to 0.2.
And my render settings.
It took me a few mins, especially with the super high detailed models ^^