IMO all the same chairs

The other two chairs could be a patterned upholstery that has either the gray or the caramel color, or both colors, or the same fabric that is on the sofa.

I have the same layout (but no TV over the fireplace) and went with a velvet sofa and 4 chairs in a mohair fabric but that are NOT the same model (2 different models - one set swivel and one set fixed). That way they are cohesive but not matchy-matchy. Still looking for the right coffee table. I used pillows sparingly to pull it all together since my style is minimalist glam. :-)

I like Patricia Colwell Consulting’s suggestion to have all four chairs the same. I think glass nesting tables would fill the space nicely but still keep the room feeling spacious. I’d try to match the frame color to the couch legs.

I’d aim at duplicating the feel of the couch.

https://www.westelm.com/products/rounded-back-swivel-chair-h6547/?cm_src=WSIShopRVI&recstrat=RVI%7CRVI&epik=dj0yJnU9WGxxOVdQQ0x3aG1vZDA1eUVzVWFYdjRJQTNVbnhOMWUmcD0wJm49dGVPQTZ3el81NEpCTTBJbUJ4dElFQSZ0PUFBQUFBR1ZsQVpZ

When accessorizing, be sure to create a connection.

I like the idea of introducing a pattern, but that depends a bit on whether you intend a patterned rug, in which case more neutral might be better.

Benzara BM194152 Fabric Wood Accent Chair with Swooping Armrests, Gray & White · More Info

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4 matching chairs will look like a waiting room. Other good suggestions in this thread, though!