Is there a wall behind your headboard? Or is there a window? Seems like a silly question, but the curtain suggests there might be a window, but you said you'd like ideas for the wall behind the headboard, so... ;-)

slate blue, benjamin moore stratton blue. goes well with browns

I think I see a vent behind the curtain, carolins. I wonder too...

')

I'd go Zen... the style of the furniture is minimalist and clean... I like the wallpaper idea for the wall behind the bed... perhaps a sea grass or bamboo framed in a rich dark molding, to coordinate with the framed mirror, but not as heavy. I agree with lamp shades needing something... the white bases are interesting but the beige shade is blah. If you don't need a lot of light bedside, I'd go dark or opaque ... even the bamboo or grass wallpaper on them, or make new ones with an unusual shape.

Some colorful interesting pottery on the head board instead of photos... create a photo area on one of the other walls.

I see a muted blue or blue green in the bath... coordinate the colors so a smooth spa like transition takes place between the two rooms. If the bath is more blue... perhaps a blue green on the walls or one to tie to the grass wallpaper.

Bedding, change to the newer spa/resort look... a colorful blanket across the bottom of the bed, and cool blue green sheets/pillow cases or a mix.

Make wallpaper shades to cover the open night stands.

Thank you for all of the comments! There is a wall behind the curtain. It was so large and white, we needed to soften the room up. I'm happy to remove the curtain though.

I also love the blue color and sea grass wallpaper suggestions. I know I can't use both and will have a tough decision choosing one over the other.

Something like this would be amazing behind your headboard.
http://houzz.com/photos/1471295