What about putting your 3 chairs at the FP area and the sofa at the far end for two seating areas?

Lovely room! Consider putting your couch facing the fireplace. (It does appear that it won't actually be centered, but it doesn't have to be.). Put tow of your upholstered chairs on either side of the fireplace. The 2rd chair could be on the wall where they have their bookcase. Add a lovely table for keys/chairs etc. Perhaps a storage area for shoes. That chair can be one where you sit down to talk off your shoes. If you need more seating occasionally, add some benches under the windows which an be moved closer to the couch as needed. Congratulations!