What's the furniture like? Do you have the bedding already? If not, buy the bedding first. Then look at wallpaper. You can get something really nice for the wall at the head of the bed. What colour does she like? She'll want input, I'm sure.

The answer is relative to your tastes. Try taking a sample of your paint with you while shopping, and see what you think: it sounds as though your room could handle some colour in the mid range to balance the high contrasts that are there already.

If you want to highlight the staircase wall then your could use earthy colours such as a yellow ochre! The wall could be enhanced even more by using suitable frames and making a good collage composition for all the photos that you have (I can see many lying on the dining table). This colour would match well with wooden furnitures

The dark blue and white combination at no.1 looks like a perfect combination of colors, furniture, furnishings and accessories to give it a complete and cozy look.