Curtains would make the window wall look less empty.

Then I would put one large piece of art on the wall to the right of the window. Move that tall vase and faux sticks thing you have by the bed to the corner between the TV and the window.

Just dealing with the bed side, for starters, you need more rug showing on each side of the bed, so either a bigger rug or two individual smaller ones. Add to the items on the bedstands -- just a couple of things you like for interest. Yes, art, and yes, curtains.

And I do think you could try that tall vase where Songbird suggests. It just looks crammed into that corner. Your instincts were spot on to try to bring some reflected light into the picture, but you can do that with metallic or glass items on the bedstand.

No matter how beautiful the windows, without curtains any room looks "not done", airy, emptier IMHO. That isn't always a bad thing, but if you want a fuller look I too would go with full-length drapes with a pattern and some color.

Don't you like color? Its so brown/gray!