Lovely print. I had a peacock feather print and I had a colour called glacier Grey behind. Think it was Wattyl . Again like your other walls it is a greenish grey but darker. I also had my prints on a charcoal wall..loved that too. As you said the picture ties in with the chairs and now it's not necessary to add more matching colours. I'd buy a couple of sample pots and paint large pieces of cardboard. With the other walls I would consider painting them in whisper white (Dulux) a very universal colour that ties in nicely with all colours.

Whisper white is so very barely warm, I think it would achieve what you are after as it is often used in cool colour schemes. You can view the full range of Dulux whites on the attached link. If you click on a colour it will give you the break down of red, green, blue content for each colour. Just remember the colours on the screen will look different on your walls as the computer uses subtractive colour and you'll be painting with additive colour. http://www.dulux.com.au/specifier/colour/colour-atlas

Stick with a ceiling white for the ceiling. That with the white trims will give the room longevity as you leave them as is each time you change the wall colour.

Plain ceiling white is a good choice for ceilings. I'm a huge Natural White fan but will consider Whisper White next time I'm painting.