A couple of questions. How many people do you need to seat in the living room on an average day? Do you need a full-length sofa or could you get by with a smaller loveseat? (In other words, does someone in the family like to lounge full-length on the sofa while watching TV?) I'm guessing the TV is in the cabinet opposite the fireplace. Can it be moved anywhere else in the room? Right now you have two focal points at opposite ends of the room--the TV and the fireplace. And none of your furniture faces either one. If at all possible, I'd move the TV down closer to the fireplace. Right now, the fireplace is kind of ignored and seems out of place in the room. Is there room for the TV to the right of the fireplace? Then I'd swing the sofa around to face the fireplace and TV. Either have the loveseat at right angles to it to make an "L" shaped conversation area, or have two armchairs, maybe swivel ones, one on either side of the sofa. Move the cat tree to in front of the half of the sliding door you don't use, and put a bird feeder right outside the door. That way, the cats will be able to lounge as they watch their "kitty TV." Then use the end of the room where the TV cabinet currently is for a desk and the computer and maybe a bookcase for storage. Or you could put the curio cabinet there.

I have nearly exactly the same layout, except add a door in the upper left corner and replace your bottom wall with wall, wide opening, closet. My room is also longer than yours - it's 18'x18'. I have added Billy bookcases with the half doors and height extensions to either side of the fireplace. It looks good and the extra storage is a godsend. I would definitely integrate a desk into any built-ins you do, like the picture kellyeng posted. Obviously custom built-ins/bookshelves are nicest, but the Billys are fine if you are on a budget. You could buy the short ones and/or cut the Billys down to fit on top of the desk. I have found two layouts that work for my room. Obviously we have different furniture but perhaps reading this will help you. 1) float sofa in front of fireplace, put sofa table with lamp(s) behind sofa, put two upholstered/leather large chairs in front of left window, float loveseat in front of slider on right, put coffee table in front of sofa, place dresser for extra storage on bottom right wall. 2) Float sofa and loveseat in the middle of the room perpendicular to fireplace with coffee table between them. Put the two large chairs south of the sofa & loveseat, angled toward fireplace. Put dresser for extra storage on bottom right wall. My TV is above the fireplace since DH wants it there, but you can easily put yours in the upper corner since you have less furniture. I would recommend that, actually, since the closer you are to the TV the less comfortable it is to look up that high. You really just have to move things around until you are happy - at least for now. The room is awkward, no doubt about it. So, when I get sick of one layout I switch back to the other. I switched back to my Option 2 yesterday. DH laughs at me but hey, moving furniture is cheaper than moving.

Having had a "setee" which is just a loveseat by another name, I can vouch for it not being very practical. Two people can sit at it, (and they will and have in my house) but unless they are very good friends or related, it's not going to be their choice, particularly if they are doing something like watching TV. Sipping afternoon tea, maybe. But if you don't need a lot of seating, then their small size is great, particularly for curling up with a good book. It's easy enough to throw in a rocker or some other smaller less padded chairs to add extra seating. I use the end chairs from my dining room set, since unless I have guests, they make it difficult to get around the dining table in my small dining room.

You might choose a drop leaf dining table with wheels so you can move it into place only as needed. With very comfortable bar seats, you might not need to use your dining table and chairs all of the time. You could try your loveseat with its back against the ?front? wall -- with door to its left and patio/balcony to its right. What other furnishings do you need to fit in this place? If you've not yet purchased them, choose undersized items and "go vertical" a tall cabinet will provide more storage for less floor space used. Having each item that can do "double duty" will also help. A file cabinet could store bank statements, bills and even photographs as well as serve as an end table (or bedside table). A tall corner cabinet with solid doors below and glass doors or open shelving above could store items you want to display as well as items you don't -- and you could put furnishings in front of it. A dining buffet cabinet could double as a tv stand; however, having a portable tv stand could prove more convenient. https://www.walmart.com/ip/32-to-65-Inch-Mobile-TV-Stand-Universal-Flat-Screen-Rolling-TV-Cart-with-Mount-for-LED-LCD-Plasma-Flat-Panels-on-Wheels/774114227?wmlspartner=wlpa&selectedSellerId=0&adid=22222222227280774471&wl0=&wl1=g&wl2=c&wl3=339502173742&wl4=aud-430887228898:pla-688392850314&wl5=9011062&wl6=&wl7=&wl8=&wl9=pla&wl10=8175035&wl11=online&wl12=774114227&veh=sem&gclid=EAIaIQobChMI1Nr026Ov6AIVgZOzCh0p8QN_EAkYASABEgIb1vD_BwE Perhaps choose a small storage ottoman with a lid that, flipped, could also serve as a table.