I don't know how practical it would be for you to do, but if this were my room, i think I'd put the couch on the wall where the tv is and move the tv to the wall across from it, mounting it on the wall, above a narrow console table (not sure if yours is narrow enough to not block the entry path). I'd then create some kind of toy storage system under the windows. You could add a chair or two to the room and a coffee table to make it more inviting. Or eventually get a sectional that could wrap around with a portion facing the windows. Or when you purchase a new sofa, get one with a lower back that could be placed in front of the windows like shown in nosoccermom's example above. I think the way it's arranged makes it appear much smaller and closed in. I don't love this room, but just showing how you might have the walkway in front of the tv instead of behind the sofa.

Furniture is an investment. I would feel more comfortable sitting on the couch that I plan on buying. If it's to hard or soft, you're going to regret the purchase. My friend gets a new couch every few years and spends very little on it. I get a new couch every 20 years and spend a lot (Ethan Allen custom). Depends on where your budget and decor frequency lies. I got a very tightly woven fabric. Have a nice long talk with your furniture person to get the type of fabric you want. It's not only if it's a "performance fabric", it's also how durable it is. If you want something that's indestructible, traditional tweed will do the trick. I used to have a cat, and he couldn't ruin it.

I can see why something is neccessary to delineate the space, but not want to reduce the floorspace. A question to ask could be how thin any construction could be. This might help with any decisions. It might be worth exploring custom options to fit a full floor to ceiling screen located as I drew out above and exploring materials - maybe frosted glass ? wooden floor to ceiling slats with glazing between? or another material between? or just slats set at an angle ? or slats that can have the angle adjusted so they can be 'open' for light to travel, or 'closed' to obscure the sight line, or partially opened? It could be a combination 1/2 wall with glazing above or slats. Another option might be to consider not having an island and placing the 'wall' at the lounge edge of the island bench so the kitchen becomes a galley style so only the dining space and bench with the stove is visable.

You could start with a professional colorist or start at a BM or SW store; I have met some paint folks who were genius with color. Our local Lowe's had a guy; really miss him. You can work with a color wheel, but I think that will confuse you by providing too much info. If you look through a paint store's color cards that feature colors you like and varying shades of them on the same card, you can take them home where the LED lighting will give you a better feel for how each works in situ. I suggest you each go to the store separately and select your paint color cards. Sit down and discuss, justifying your choices and see if you can narrow the cards down to 2-3 for each of you. Then you can order larger samples from www.samplize.com so you can see them on different walls in each room, in different lighting and weather conditions (sunrise, sunset, nighttime, mid-day, raining, sunny, gray) to nail down how they will work in your room, with your lighting. You can also acquire info on other colors, not on the cards, that are designed to work with them in a complimentary way. Now, part of selecting color (really the last step in most decor projects) is to consider your fabrics/textiles, which can't be changed as easily as paint can be. If you have your rugs, upholstery, art already it will be easier to do. If starting from scratch, you'll need to start mood boards for the furniture you plan to purchase. Do you have samples of the flooring you've chosen? That's part of your "board" too. It will be easier to make decisions on the individual rooms if the flooring is already installed. Placing the color cards with the board will help focus in on the best color for your place, and it may not be the one you have in mind right now. Be sure to take a cushion or matching pillow from the navy sofa with you as you shop for color and other fabrics/textiles. Big job but worth taking your time!