That is such a beautiful room! I love the cabinet and the coffee table with the blue finish on it! Those are amazingly beautiful windows and during the day are breathtaking, I bet! I am not sure I can really add any suggestions for covering them at night - in our family room, I lived for a year and a half with nothing on the windows and at night it felt creepy - we have woods in the backyard as well but it felt creepy without anything covering the windows. We ended up getting Plantation Shutters - pricey but beautiful and I love them. During the day they let in as much light as you want - at night they completely close and you feel cozy inside without the blackness of the windows. I don't have a pic to post at the moment though. Sounds like you wouldn't want shutters though - it sounds like you want something minimal during daytime.

I would make a cornice out of foam insulation board or plywood in the arch shape. I'd paint it to look like a road with a double white line in the center and attach something car-related--red brake lights for example along the arch and hang curtains as daisyadair has described.

If you like Romans, take a look at jcp.com. They have some double romans (I got Spencer II) so there is a sheer behind the light-filtering shade, operate independently. The cords can be a hassle (2 sets) esp. on the 72" long ones I got for my slider. But on normal windows they're OK. I really liked the "double Roman shades" they had last year (no name) for my BR, DR, and study, but they don't seem to have the same ones. The headrail was slightly different from the Spencer II. I think the last time I visited the website they might have had a new (Jackie?) roman that might have been a double too, in an ivory color that might look nice in your kitchen. HTH. Sheers down

If you really want them you need to remove the mirrors. The mirrors aren't reflecting anything worth seeing twice. Even if not closing the curtains they need to look like they can be closed. For the rod measure the width of the window and add 1 to 3 inches for each side of the window. Multiply the rod length by 1.5 for minimum fullness, 2 for medium fullness and 2.5 for an extra full look. For example, for a 36-inch rod, your measurements would be 54 inches for minimum fullness, 72 inches for medium fullness and 90 inches for an extra full look.