I like the idea of grey couches but look for a lighter grey since there is already a dark floor and dark grey tiling on the fireplace. And what color accent chairs would you be looking into?

https://homesweethomestore.com

I’m not sure what would be best for accent chairs. Any suggestions ?

Maybe you can add a bit of color with the accent chair, as you have plants adding a dark green or blue would help to animate the room and create a focal point. Also, are you thinking of adding a coffee table? It is the remaining element that is missed in your current design. I would suggest adding something neutral like a Barcelona table. I'll attach some ideas :)