You might want to try the gray family, but don't be afraid, it doesn't have to be gray. Gray is the new neutral tone. Try a slate blue in a light hue. Just go to gray tones Sherwin Williams has a huge selection. Just something with a slight gray undertone or puddy. It won't come up yellow at all. Chocolate and blue are one of my favorite schemes.

The faucet pictured is by Altman.

I don't think tiling the walls feels traditional ... it's more a matter of your taste. One interesting option would be to do a back-painted glass. If you type that into a houzz search you'll get lots of looks. This is lovely in the streamlined modern look you have going on, and can be done in any color (a really pale icy blue would be stunning). In a completely different direction you could do a stone wall to add some warmth and depth. For instance ... Or ... These come in lots of color and cut options. I can't quite tell in the photo ... are your counters stainless? If not, how about a great metallic, or a metallic and gray combo? Just a few thoughts!

Suezbell, we have asked to explore that option, which means increasing sq footage inside. That lone window is currently in our master which sits at the back of the house. We asked for a way to have a view of the woods across the street w/o adding in the awkward sitting room to left of chimney. I think the longer gable may present other issues as well such as where do windows (which are currently centered) get placed? That js for him to figure out though so we will see!