based on the drawing, the wall where the bed is. HOWEVER, you mentioned that this drawing is not a true depiction of the furniture you will use and the wallpaper. if that is the case, i think the wall paper can work on either wall, it all depends on how busy this wallpaper is and how "plain" the bed is. if you go with a busy wallpaper behind the bed, you may want to keep your bed and bedding on the minimal side so that there is a good visual balance to the overall composition. if you go with snazzier bedroom furniture, then a busy wallpaper may be a bit much and you may want to put it on the other wall or use a textural option to serve as the bed's background rather then another focal point.

Hi thank you both for replying! My bathroom is still in the making, Unfortunately I just paid for the grey tiles so I'll have to stick with them.. Everything is white, the door handles and sides of shower/sink is silver. In the pic there is a bare wall on the right that needs painting. What colour do you think I should paint it? This will set the theme for the rest of my unfinished bathroom... Thank you

I think that bathroom really suits the colours. If I was intending to stay in the house long term then I would do it.... why not enjoy the colour and look your love. If you are going to sell in a few years and you are thinking it might be too bold then maybe just do one wall - after all the new owners can paint over it.

Thankyou very much!