You may want to try picking a shade of navy from the SW or BM website that is similar to the couches, and seeing what colors they suggest. Based on the trim color, i would think off white or a light taupe would work best. Try posting in the home decor forum. Lots of great ideas there.

I don't know what your style is but you could use a brighter warm white for a clean sophisticated look but if you like bright and cheery a yellow, orangish shade would be awesome. Can be a pastel if you don't like a heavy color. Mostly you need some color in the room. The couches are nice but need color to wake up the room. Curtains? Pillows? In colors that compliment the navy blue. Some pink, orange or yellow are good. If your into it a nice area rug would warm up the space.Some greenery is always a help wether you like plants or fake plants.