I am absolutely in love with my kitchen's green house window that is over my sink. Mine faces west, so it gets the late afternoon sun and the last bit of light before the sun sets.
I find that this is ideal because when it is hot in the summer, the early morning sun doesn't come in to heat up the house. I still find that I need to close the blinds on particularly hot days, but overall the western facing window is the way to go!
If you are considering putting in a green house window, I'd keep in mind that the window should be placed somewhere where you look often, such as over the sink. Even if you have a gorgeous window that faces west, it will be a waste if it isn't somewhere where you eyes naturally gaze.
A western facing green house window is ideal for raising succulents and other hardy house plants because of the steady warmth it creates.
Does anyone have any other experiences with green house window placement?