Carry the same accent colors (pillows, throws, etc.) in both seating areas. Use the same types of lamps.

If you would like two separate seating areas (one for viewing the tv and one for the fireplace), then two area rugs will help define the spaces. You can do really anything but shag. You carpet is already quite plush that I think a flat weave would look great. If you don't want two area rugs, at least use an area rug for fireplace.

Even if you have 2 seating areas they have to relate to eachother right now they are like separate rooms the sectional is making a wall so try turning it so that wall disappears or if possible get a sofa instead with chairs so that the spaces are really one with 2 areas You might have to rethink where the T.V is and maybe try putting it in the same space as the fireplace. An actual detailed floor plan would be a real help.

Your windows provide wonderful light. I think I would try to highlight them. Remove the valance and add crown molding. The sofa should be turned around so it doesn't face the wall. If you are going to socialize when the TV is not on, it just doesn't work. Can't see where to put the TV as the photos don't show the fireplace wall. I would start with this and see where it leads.

I like your ides of creating separate spaces within your large rectangle. At first glance, your photos give off a man cave vibe from the sectional placement, and the carpet, valance, and furniture choices. Your sectional closes off the TV viewing area, making it look less inviting from the kitchen. Can you separate your sectional pieces, or slide your sectional counter clockwise, in a way that everyone can still comfortably watch TV? Accent Pillows and throws on the sectional will soften its look.
Your TV seems to float on the wall because nothing is under it and there is empty wall space between it and the flanking windows. Will your credenza fit under the TV?
Few folks sit in a chair to stare at a fireplace, so try facing the 2 chairs towards each other for tête-à-tête or facing into the room for reading, and add a small colorful rug to anchor them to the fireplace.
All the furniture is the same height. Can you add some pole or table lamps and art work to help the eye wander around the room?

I wish I had so much room. Lucky you! You need to use rugs to define separate areas.

Please submit a floor plan or at least give measurements. I think your furniture arrangements need more than tweaking. A photograph of each wall would also help.