I would do top-down/bottom-up shades. You'll keep the look simple and you'll be able to lower the top half to see the night sky. They are also available with room darkening fabrics.

@yourchigirl Thank you for that advise and sorry for taking so long to respond! I hadn't considered centering the credenza offset on the wall section beside the window, but I like it. Another option... instead of keeping the credenza behind the desk (which pulls it more into the center of the room) might be to put them on adjacent walls. If credenza stays and desk is turned 90* to face the window it can be set closer to the 10' wall so that the back bookcase will still be seen although not straight on from the entrance. Like this... Not sure if the tall bookcase would really be necessary with this setup. Maybe just move the floor lamp to the front right corner instead of the back?

Instead of wallpapering, I’d avoid the trouble and cost, just paint a great paint color and add colorful curtains to hide the clothes. Add a large piece of art on the far wall and unique lighting in ceiling. It will be a lively space and if landlord requires, slapping on white paint before you move is pretty easy. Also replace lighting to the original and take your light with you.

You'll have to sample because you have beige and gray in the floor and it's difficult to tell from a picture on a monitor exactly what will work, but I suggest you look at BM Edgecomb Gray. SW Accessible Beige is close to EG. But I think you might be better off with a lighter color for a hallway, so look at BM Soft Chamois too. But while you say you're looking for a neutral I encourage you to look at blues or greens which would be more interesting - maybe in the treatment rooms.