Wallpaper for Girls 4 and 6 yrs old

[PastaLaFeasta]

With the new year looming I'm gearing up for this project. DD will turn six in May and will be able to have a bunkbed which will be great for space saving in our two bed flat and their shared bedroom.

I'm going for a classic white bunkbed and some white shelving (Ikea Kallax predictably) alongside our existing wardrobe and drawers in a darkish wood. Its a dark room with a single window out to the side of the house so I need to maximise light, I'm considering painting some walls in a light colour, perhaps an off white with a wallpaper with light background on the walls behind the bed and shelving.

Preferably the wallpaper will have pink included and be fairly girly to suit the girls, although reasonably tasteful if possible. I like the Lilleby birdhouse wallpaper but we have a lot of bird and floral type wallpaper already. Any ideas? And any ideas on maximising light and space. Thanks