Here is an idea: A simple grey with a base and light yellow pattern over a newly installed southern yellow pine similar to the color of your floor.

While grey is safe, I think since everything else is so neutral, this might be a great place to bring in some color if you are so inclined.

Take a cushion with you when you go shopping for a rug.

The chair and ottoman in the window pane fabric... what color is it, green or grey?

The chair and ottoman are charcoal

If the chair and ottoman are charcoal then the only color I'm seeing is green marble fireplace surround. I'd consider added more green, light blue and plum. like the color scheme picture below.[houzz=]

I think with the window pane pattern you may be better off trying rugs with asymmetrical, floral, or tonal designs. Large geometrics, like in the picture, are probably too much.

I would ask you what are your favorite colors? Your space is totally neutral so you can add any color you like! Don't limit yourself by your throw pillows they can easily be changed. Find a few great rugs in colors that you love. Bring them home to see which one you like best. Also, make sure you choose the right size rug - you want a large rug that will fill the seating area. There's nothing worst than using a 'postage stamp' size rug in a large room. Hope this helps!

http://houzz.com/photos/20771279

How about this? Too boring?...