This week went into figuring out the lighting. Adding atmospheric volume gave it that impression of dust visible in the light shafts. This adds to the setting, and in my opinion instantly gave it a rustic feel that it had been lacking until now. Adding the stained glass windows also now gives the room a reddish tint, which counteracted the blaring artificial-looking white lights that previously poured in through those windows.
The stained glass windows were a bit of a workaround themselves. I previously had ornately sculpted glass windows. I had used thick polys for these, instead of planes. Attempting to add the stained texture to those had a baffling effect, where the texture simply wouldn't show but would turn the glass wine-red. I feel that they would have added a nice touch of varying the light refractions, which isn't something a simple plane can achieve.
For the coming week, as much as the lighting leaves much to be desired, I have decided to temporarily set it aside in favor of filling up the room a bit and clearing up topo , textures. Once it feels fuller, I can punch a hole in the floor for the flowerbed once more, work on the grass, and then get back on the lighting!