The photos of the sofa isn't apparently Schaeffer's LR -- just to show the sofa. Actually, the sofa is too large for the space. being a sectional, it can be separated. Try 2 slipper sections together to create a loveseat in front of the window, facing the remaining sofa opposite. Yes, a glass table. You already have enough "heavy" pieces in this room. That's all the furniture you need, with some floor lamps.

Definitely an area rug to anchor the space. Big enough for all front feet of seating to be on the rug. Bigger is better.

Budget allowing, sell the sofa and buy something smaller scale. And cloth. If you want to keep this sofa, to make it classy, go minimal. No fussy stuff. sleek, streamlined, modern. I sure hope your style isn't traditional!