If your walls are gray ad new leather sofa is gray, bring in some color with the chairs or rug, unless you want to keep everything neutral and just use pillows and art for color. Many colors will go with your grays. Turquoise, orange, yellow, blue, navy or a combination of 2. They are pretty much interchangeable.

If you go with a solid or plain rug, then you can use prints or patterned colors for the chairs or get lighter gray chairs or off white and then pop with art or pillows in above colors. If you want to go with more color in the rug, then add chairs in accent solid color and bold printed pillows.

I'm a fan of neutral furniture pieces, rugs, and draperies (all of which might be expensive to update), so I prefer to incorporate accent colours with decor pieces, art, lamps, and pillows.

The beautiful seafoamy colour on your kitchen walls would be my starting point. Either match that colour, or find it on a paint swatch and go lighter and darker while mixing in with whites or greys -- a touch of berry or coral tones would pop nicely if you need a little vibrancy.

Beautiful floors, by the way! :-)

Thank you all for the great ideas

There are so many ways you can go both style and color wise; if you haven't already looked at living rooms with grey couches on Houzz photos, they may provide color scheme/decor/design inspirations. You may want to use an on line room planner as you have an unusual layout to consider so that when you are selecting your furniture it is best suited. Select your rug after the seating so it can work with your size/layout. There are so many colors that would suit - it really depends on your taste and how you want the room to feel and you may want to start saving ideas from magazines or create an Ideadbook on Houzz and you'll start to see what you are leaning towards. Enjoy your new home.