The stained glass windows were done with quite a bit of work, including having area lights both in front and behind them, having very high translucent and reflective value, and making them glow. The actual colors are a photograph of an actual rose window of a french cathedral.
Thank you very much for the comments on the quality of light and the floor. It is still in progress, so not nearly perfect, but your comments allow me to make a kind of "to-do list". Thank you!