I really like the way you have lit this scene. I'd be interested to know how you get those shadowed areas. Are you using tight spotlights in this version?

By the way, it crossed my mind that your problem with the spotlight not showing up in Preview might be due to the OpenGL 8-light limitation. Perhaps you have a number of lights dotted around but not doing anything, and the one you were trying to set up was number nine? Just a thought. Of course this would still not explain why the render was coming out unlit....

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)