I think a cool, dark accent color behind the fireplace would bring a lot to the living room. The dark accent wall, fireplace and custom wood floors add warmth to this open, modern living room. Big windows flood the space with tons of natural light.
Again - check out blue wall and beige sofa - and this blue is darker and closer to your original blue - I think it would look great: Blue paint color Seaworthy by Sherwin Williams. Perfect for living room accent wall.