A few suggestions (plants not specific as don't know where you are) ... Think I would paint door, door frame & posts just white. Shutters, one of the greyed teals. Explore color on one of the paint mfg. websites where you can upload photo (a better one w/ less shadows) and see changes ... like @ Valspar.com.

So, it's 15 ft from window to fireplace? Is that the entry to the left of the fireplace in the last pic? That first pic Rawketgrl posted shows the seating area on an angle. That might work well in your room so that the piano and fireplace can be the focal points. An upholstered chair and table can to go on the end by the window. I like Acm's idea to bring in a game table, which can be just to display a few things if you want. The couch can be perpendicular to the fireplace, with the bookshelves behind it and couple of chairs facing the fireplace. Or, turned 90 so that the couch faces the fireplace. Chairs on one side, or both, depending on the room available. A table can be by the windows for display of some pretty things or used for games. Plants, tables w/ lamps to fill in the holes. A large rug will anchor your floating seating area. My combo family/living room is similar in size to yours. My seating area floats in the middle facing the fireplace, which is on the long wall. The back of my couch faces the entry because the shorter direction didn't give me enough room for my couch and tables. Around the perimeter is a huge lighted cabinet, a table with lamp, and two dressers that hold music/media with the tv on top.

Oh. Like magic. :o) For sanitary reasons, I’m not sure what you could put there. How about a couple of floating shelves on the wall up above? If you don’t need the storage/display space, I still think just an art print would do it. It is a bit of an awkward spot but its location right next to the toilet kind of gives it an ick factor. Sorry I’m not more help.

Well, I was going to suggest the ubiquitous fiddle leaf fern, but looks like you have a cat, and they are toxic to cats. You might Google plants that are non-toxic to cats and see if anything grabs your interest. I think some palms may be ok with cats (and they can grow fairly large), or you might look for a contemporary plant stand and just sit a smaller plant on it -- maybe a giant tropical bromeliad or something along those lines. That said, if your cat is prone to pester plants, it's probably not a good idea to include one in your décor. (Definitely don't put a fake plant in this pretty space.)