This may seem like an obvious solution, but many people forget how much vertical space they have on their walls. This should be taken advantage of! Layered shelves help utilize wall space, and will also create an organized modern look.
Mirrors are cool! They reflect things, they would also help detect if you had any vampires in your house! (A very needed added bonus!)
Mirrors help your house feel spacious!
Even a picture of a mirror can help your house feel more spacious. (I'm not sure if a picture of a picture of a mirror works though?) I think looking at this blog post makes my house feel more spacious! Give it a try!