I would go with a warm 'greige' color (grey/beige). and the wainscoting always looks classic just white. but you could definitely go with a darker greige shade if you aren't fond of the white. and for the window, I would take the existing blinds down and replace with roman shades, or something else with a soft neutral color and/or have some drapes for the window (3rd pic). if you really want to hide the window, you could put drapes on the whole wall and cover the window

I would go completely unconventional and paint the wainscoting a color present in your duvet cover (and abandon the idea of keeping it white). It will add warmth and create a much more welcoming and delicious bedroom feel. The blinds above your bed need to be replaced with something softer - the idea of roman blinds presented by jennyrf is a good idea, or even something softer like the french pleated drapes shown in her Glenwood Residence photo would be wonderful. What I like about the pleated drapes is that they will add some much needed richness and softness to the room, while doubling as a headboard for your bed. Bedrooms are such sanctuaries, and I am excited to see yours transformed into one. Please post images once you've made some selections!

What about this wall?

If you are after romance in the room you could add Priscilla style curtains which would totally suit your duvet and go with a colour such as BM330 - Sombrero on the walls (grey is not romantic: think about the saying "it's a grey day" and you will see what I mean). No reason you couldn't paint the wainscotting a warmer white or even a cream. BM's Hepplewhite Ivory is dreamy.