With all that lovely wainscoting, I would consider light weight fabric for inside mount roman shades.

Ditto the above... beautiful room.

I would consider a valance like this one ...set higher so as not to obscure too much of the glass but to add some softness and formality to the room.

I would use curtain panels from both side of windows.

I would go with a linen curtain that is in the same color family as your paint. So perhaps a khaki or beige. That will add warmth without taking away from the beautiful wood work.

Love your space!!!

Properly hung drapes will require moving the art. I think inside mounted shades in a soft fabric or fiber will do the trick. Are you considering a rug under the table? Looks like you have plenty of room for one. It would add more softness, as well as texture and the opportunity to inject a bit of pattern.