While grover’s solution is a good one, I think the niche is screaming for a built-in the full width of the niche.. Our house has one, with room for a 65-inch TV (my husband bought one within 5 minutes after moving in!). It has doored cabinets along the bottom and shelves on one side. I added another shelf on top of the TV area, to fill in the blank space there — and to prevent my hubby from buying an even larger TV!!!! I think it would be perfect for your space.

Your previous post here on houzz.com related a "surprise" when you got pricing from a remodeler. Your architect will have a general idea about which alternatives are simpler and less costly, but when it comes to the question of "how much?' you'll need to rely on a remodeler to get an accurate answer. Get your remodeler on board at the same time as your architect so you can benefit from real-world cost data to inform the design. If not, you're likely to spend money on plans for a project that doesn't get built.

How many people will be using the space and for what activities? I'm a big fan of two sofas and two chairs. Love seats sucks. Four chairs seems like a lot, but if you are having gatherings of people who don't want to sit so close to each other, it could be smart to have a sofa and four chairs. It sounds more to me like a formal living room set up than a family room though.

Also , measure how far away from TV wall the seating should be in order to see it well— which depends on TV size as well. See if then the furniture arrangement will still incorporate the fireplace. It might not be completely centered but still look ok. I like that you are putting TV on wall, but in rooms where fireplace is too far along the other wall, people tend to keep furniture back by fireplace and a looong way from TV. This is the problem with builders still making rooms with fireplace a centered focal point when buyers plan to use the room for TV. To me there’s an issue a when major seating is perpendicular to the TV and viewer has to sit sideways or crook neck. This is less a problem for fireplaces , which don’t actually need you to “ focus” on. In a longer room the TV and fireplace seating can be separate groups, but I didn’t think from your measurements that will work here. I’d enlarge up your floorplan and cut out little sofa & chair rectangles , also tables & ottoman and push them around. I’d play with that a lot before buying, as the arrangement and measurement specifics ( really knowing whether you can use 88” sofa or not, what size chair, etc) may spark ideas for which brands & styles you should shop.