I think they look good uncovered. Is privacy an issue? Your house is very bold so I wouldn't get anything fussy. Perhaps just simple window film in a rice paper or plain frost would look good and you could carefully cut if in graduating stripes to give it a contemporary vibe, or just cover all or part of the window.

You could also create inset frames of wood and stretch a lightweight fabric all around and staple in back and then pressure fit it in. Or you could hang something interesting in each window, like stained glass (Prairie style?) laser cut wood panel, Pukka shells, plants, etc...

Both would be fairly inexpensive. Cellular blinds or something would be an option, but I don't think you will be up there that often to raise and lower them.

If you didn't mind a permanent solution, you could use glass etching cream, but there is no going back if you do. My stepsister did this and it did look nice. You could even mask off a geometric pattern or something. A less permanent version is thinned down paint (perhaps the color of the light walls) sponged on. If you don't like it, it can be gently scraped off with a spray of water and a single-edged blade. Rubber cement can also be used as a mask, but the edges won't be sharp.

Is that a balcony on the right side?

I wooden woven blind of some type is what I think would look nice....IF you really need to cover them. I would imagine you would have to get something with a remote control operation, since they are so high. If not I would leave them alone and put a tall vertical piece of artwork above the mantel with all your bright fun colors in it! Love the house...it looks like a fun place to hang out! :)

Yes, that's a balcony on the right side.

Thanks for all the suggestions. I didn't consider hanging stained glass in the window but will definitely consider it. The eastern morning sun comes through those windows and I think that'd look amazing.

Anything that I'd have to manually raise or lower would definitely be out. Once something is up, it more or less will have to stay were it's at. Privacy isn't really an issue with them.

We're definitely looking for something tall for above the mantel. I've seen some great ideas here on this sight, but it's hard finding out where to purchase some of the stuff.

Thanks!

Love your bold color choices. The mantel seems fine to me. Its not really necessary to do anything to the windows, they give the room light and add a modern feel.