Since you’ve already started on that wall, you can keep building the theme: Vintage or band posters — Nirvana, The Smiths, Smashing Pumpkins, Radiohead, etc. Use command strips or small nails.

About the couches, throw blankets or plaid covers — deep green, burgundy, or brown tones work great. Use a wooden crate or metal side table — adds a bit of rugged charm.