Depending on the size of the bathroom and the amount of light, I would have no problem going with one wall being a dark color and maybe using half tone on the other walls. It looks like you have a tall ceiling, so keeping it white will allow for your to have the larger feeling. Painting the ceiling the same color as the walls will close in the space. You want your vanity area to pop. Earth tones work well and don't fight with other natural colors. I always tell my clients, keep in mind it is only paint and if you don't like it, you can just paint it again.

Lovely bathroom. I'd remove the things on the shower wall and leave nothing there. Allow maximum light to come through. You are smart to have chosen neutrals. For a pop of color, find a picture you like for the wall to the left of the sink. Then select a color from that for solid colored accent rugs and towels. For the wall above the shaver, add a towel ring so a towel hung there will cover the outlet. For the angled shower wall, find a metal piece of artwork that compliments your hardware. Metals don't have to match, like your towel bars and light. So you have that freedom. Just shop around and you'll find what you like. Take your time.