Just a quick suggestion, if the plumbing works place the WC under the staircase. And place the door so it does not open towards the living or kitchen areas. Please also post some photos of the house as it looks from the outside.

We just painted a color called "Latte" over the dark red walls in our place and we keep thinking that someone left the light on! It adds that much light to the place as the red was just sucking out any light in the place. Find a color you like more for that wall and repaint...and/or maybe add a ceramic tile backsplash? It will make it feel brighter in there immediately as you will get a lot of light reflection. I love the idea of sage green with your cabinets.

A niche would be a good way to add some drama without infringing on your circulation space. It doesn't have to be deep to be effective. You can do one simple vertical rectangle, and line the back with a mirror, or add some colour with paint, wallcovering or wood. It would be great if you could also add a recessed light fixture at the top. The attached images are perhaps too busy for your situation, but it gives you a good idea of what can be done. Good luck!

I am looking for help on chosing a colour for my kitchen walls. My kitchen units are painted with farrow and ball "satin slipper". Floor is American white oak tile. Dede