Reddit mentions of HPD Half Price Drapes BOCH-LN1855-96 Faux Linen Blackout Room Darkening Curtain (1 Panel), 50 X 96, Oyster

I couldn’t find if you mentioned what your budget was, but assuming north of $2,000 if replacing sofa, tv cabinet, and coffee table. I’ve included links to some of my favorite pieces below that are very reasonably priced - I think these are on the lower end of the price spectrum for decent quality.

Layout:

In a smaller, less formal living room, I actually don’t mind a tv above the fireplace because it usually lends to a better seating arrangement. That said, since you’ve mentioned you don’t want your tv above the mantle, I’ll offer an alternative:

• three person sofa in front of window
  
  
• leave TV where it is, mount on wall above new console.
  
  
• I think two upholstered swivel chairs would look good - one to the right of the sofa and one to the right of the console. By flanking the mantle on the far side of the room you’ll add some dimension/definition to the space and highlight the fireplace as a focal point.
  
  
• Alternatively, I think a swivel or upholstered chair on either side of the tv console would look good, but the aforementioned layout lends to better tv viewing.
  
  
• I would add a large rectangular coffee table directly in front of the sofa aligned to the middle of the fireplace.
  
  
• the built ins are a good idea, but a pair of etageres (open bookshelves) may be far more cost effective and will achieve a similar look.
  
  Colors/Fabrics:
  
  I’m making some broad assumptions based on your statements and choice of Sea Salt as your wall color, so I apologize if this isn’t what you’re looking for.
  
  
• Sofa: I would stick to a neutral for your sofa. This will be your biggest purchase and you want something that will go with different schemes down the road if you decide you want to mix it up. I love a creamy linen or cotton fabric.
  
  Rhoden Sofa
  https://www.wayfair.com/furniture/pdp/breakwater-bay-rhoden-sofa-w001205908.html
  
  
• Chairs; I’m partial to neutral cream color scheme for all my furniture because it gives you more flexibility to add colors with accents, but if you feel inclined, your accent chairs are a good place to add color/texture. I would get two that match each other (but not the couch).
  
  Sabine Swivel Armchair
  https://www.wayfair.com/furniture/pdp/bernhardt-sabine-swivel-armchair-bht4869.html
  
  Lucas Swivel Armchair
  https://www.wayfair.com/furniture/pdp/rosecliff-heights-lucas-swivel-armchair-w000229739.html
  
  
• Rug: something neutral, like a sisal or jute, will add texture but not too much distraction. If you really want a pattern, I would scour eBay for an Oushak that has muted tones that mimic the other colors you want in the space. I would go with as large of a size as your room allows (minimum 9x12, 10x14 if your space wlll allow), such that you have about 12” between the rug and the wall.
  
  Curtains: unless they’re custom made, I think patterned/colorful curtains are more often than not the #1 that gives a home goods or target purchase away. I would stick to a neutral. I have the amazon ones linked below in oyster - they have weighted bottoms and look just as high quality as anything at PB or RH. Also - I would get a more substantial rod in black or weathered wood. Target has a great knockoff that looks like wood but is actually metal for $20-$30. Get 96” curtains and hang them about an inch below your moulding/ceiling.
  
  BOCH-LN1855-96 Faux Linen Blackout Curtain, Oyster, 50 x 96 https://www.amazon.com/dp/B078JLSG5V/ref=cm_sw_r_cp_api_i_-.oDCb7QH6VSB
  
  Pillows: this is where you should add your color. Instead of going to home goods or target, shop around on Etsy for custom made. PetajaFiberWorks has done some great work for me and I love their fabric selection. Very reasonably priced too. They’re around the same price as big box stores and you can get much higher quality fabrics/patterns. I think a blue or sea foam scheme would look great and would bring out the sea salt in the walls.
  
  https://etsy.me/1ASCzsL
  
  Other:
  
  TV Console: I love a weathered, light wood finish, I would find something that looks more like a dresser or a buffet - just be mindful that you have adeuqtE space for your TV equipment.
  
  Drummond 4 Drawer Sideboard
  https://www.wayfair.com/furniture/pdp/rosecliff-heights-drummond-4-drawer-sideboard-rclf2854.html
  
  End Tables: I think two round end tables would balance the squareness of the room/sofa. Again, I like a like weathered wood finish, but your call.
  
  Mantle/art: A big rectangular or round mirror would look great above the fireplace. You could leave the mantle bare or put some matching vases with greenery on either side to add height/flank the mirror.
  
  Lamps: I think a creamy, ivory colored ceramic lamp with white or natural linen shades would look great here. Or perhaps a blue and white chinoiserie lamp.
  
  https://etsy.me/2Veo0jU
  
  Bloomfield 22" Table Lamp
  https://www.jossandmain.com/lighting/pdp/bloomfield-22-table-lamp-bl8070.html