To really make a space feel unique it's important to mix up what you put on the walls.
Artwork adds personality to a room. You can use a piece of artwork as your inspiration for the whole space. It often determines the color pallet of the space and can really set the tone for the design process.
A mirror make the space feel larger and brighter. Just be sure that is is reflecting something of interest and not just a blank wall or door. It should reflect something of beauty to reflect it around the room
Adding texture is also a great idea. It's brings in another element to add interest to the space.