Here's my dry fit of the door frame (from the dining room side) with some "stained glass" pieces (these are just paper printouts) for effect:
This doesn't look so bad, I guess. It just still feels a little too modern to me, and I think it's the style of that arch. And then, of course, I found this picture, and suddenly the idea of making these transoms square instead of arched seems to fit much better:
So I'm still debating. A rectangular transom would certainly be easier, as there are far more rectangular glass designs than the half-arched ones. Plus the trimwork would be easier. I might also need to scale down the size of trim on the door panel a little bit still as well, and maybe that will help add a more antiqued look. Meanwhile, my transparency film should show up today or tomorrow,
which means I need to resolve this debate quickly and get a move on!
More and more I think I'm leaning toward the square transom...
Update: I adjusted the trim size on the door framing and I like that much better! I think I will go with the square transom too. The arch doesn't look so modern now, but finding a stained glass pattern to fit this particular arch shape has been very difficult. I haven't given up on it completely (it looks remarkably feminine and delicate now, I think) but I think that transom is going to require some more work.