Very nice image! Great modelling! I'd agree, a spot of color would be nice, and you have the perfect opportunity for it in the stained-glass window in the rear of the cathedral. I'd move your light-cone sources away from the camera so the cones are streaming more toward us and to justify adding the color information in your stained glass window to the glow channel. I don't think you'd need colored light cones coming through the stained-glass; maybe a bit of an aura filter, though, to give it more punch.