I did something similar to Mike’s (before hearing how he did it), using a sun for shadows and a hemi to light the dark areas. (I used to do it this way in another modeling application I used to have.)
I did that as well. I’d played with the point lights in the earlier tutorials just to light up the scene a bit. Once I heard that Hemi existed, a (this is the idiom, sorry) lightbulb went on!