Trying to achieve a moody home office... Help!!

Here's the current setup. The desk & credenza need to stay. And I love the wall/shelf color so that will be staying. Inspiration pics included... How can I make this look cohesive? The shelving is already busy so I don't know what to do with the blank wall. Maybe paneling? And no idea what to do with the window treatment. The current roman shade is awful. Curtains? The bench under the window is for the cat. I think she needs a cushion. And no idea what to put on the ground under the bench!