I would want to get some pattern in the room to make it more interesting....maybe swap out the solid brown curtain for one with pattern to bring some accent colors into the room. Then you can select one of the accent colors to paint the wall if you want to do that. However, the space looks pretty small and having an accent wall will only make the space look smaller, IMO.

For a paint color, you might look at a paint swatch that matches the bedspread and then go a few shades lighter to get a softer shade of that taupe.