Jim,

Remember, you don't have to set the sky setting to volumetric, you only need to use volumetric settings for your spotlights. That's why I changed the directional light to a spotlight.

During daytime, I don't think interior lights have much affect on the scene, that's why I try and keep the number of lights to a minimum. It would be interesting to do a dusk or sunrise scene like the PHOTOGRAPH above.

The friend I mentioned to you, his name is Syd Mead and he's quite an accomplished illustrator. His photo reference library is amazing. He keeps every picture he's ever ripped out of a magazine and files it away, and ends up using them for composition studies, lighting models and color schemes. (Google Syd Mead).

It's probably one of the best ways to learn. Find a picture and try and duplicate it.

-C