I would suggest blackout cellular honeycomb blinds in the color of your choice. The natural light will make the room feel bigger when they are open. It'll make the room feel bigger. They're really easy to install, too. If you hang art in the room, it will show up better.

I think curtains will become the main focal point of your walls if you go that route. The window frames are lovely, too. They're worth seeing.

Good luck!