I'm not sure what you mean by "what to do with the angled walls/ceiling". They are what they are. Presumably the bed will go on the wall opposite the closets. I'd probably put in a low platform bed with built in nightstands. Then you can add table lamps for reading that sit low on the nightstand, like a globe light or similar.

If you're doing a brick accent wall on the slider door wall, I'd keep the walls a bright white. Or you can do a really light sage green like Benjamin Moore's Healing Aloe or possibly their Silver Marlin. Keep the ceiling white. Paint the closet doors the same color as the walls so they blend in.

Thank you, Sabrina. I appreciate your suggestions!

I should have re-phrased my caption. I apologize. I am seeking advice on if I should paint, shiplap, add more brick, etc. to the walls/ceiling.

The built-ins were installed by the previous owner and are from IKEA. Unfortunately, the surface is not ideal for painting.

Furniture placement will be as you mentioned.

^^ agree 100% with @Lynn Brenner

I would keep it simple, only paint.

Paint the ceiling Bright White and the end walls a color for some interest.

I personally would paint the window end with a tree limb or few with leaves and bird... as if you are peeking out of a tent into the wilderness. or find an outdoor mural.

I just came across this and like the look of the walls and ceiling painted the same color. It's a bit dark, I'd go lighter but uniform it will be!

No added brick anywhere. Just plain white walls everywhere. Let the architecture be the feature that you notice, not adornment gimmicks that detract from the architecture.