Hey guys.
For those of you who don't remember - I was the one who modeled the whiskey glass & ice cubes, and I'm quite honored that you all use it for your renders.
I'm not quite familiar with the rendering program/plugin you're using, but in the I rendered it with FryRender (found at: http://www.randomcontrol.com/). I saw you were discussing the lighting methods for the rendering, and I must tell you (what you probably already know) - LIGHTING IS EVERYTHING. In my render I didn't use any light fixtures. Instead, I used an HDRI, for IBL (Image based lighting). Meaning - a 32 bit image (.hdr format), which is "wrapped" around an imaginary sphere around the model, and is applying light to the entire model. This method is extremely efficient, and gives awesome results, in less time.
About the materials - Fryrender uses it's own materials, and it doesn't rely on the ones from sketchup. So, it doesn't matter what material you specify in sketchup (color, transparency, etc.) - the one you pick in Fryrender can be different.
I don't know your rendering program, and I don't know if it supports IBL, but from what I see - it gives pretty nice renderings.
You can check out more renderings i did with fryrender, and observe the lighting methods:
http://www.flickr.com/photos/41836385@N07/sets/72157622515799491/