Lighting and Rendering advice

I spoke to Boaz Livny, My lighting and rendering professor about using one of the shots from my storyboard as my final project for his class and he had many suggestions about my thesis in general.
First of all the shot that I had chosen to do as a lighting and rendering final piece was the first opening shot with the God Rays and the fog and the humongous trees. The first bit of feed back was to do the God rays and fog as a composite and not generate it in 3D. I got the same feed back from Adam Burr (Dynamics and Particles professor). This is great coz now I can concentrate on the other effects and Mental Ray.