Are those windows crank out Florida windows and do you open them regularly? You have two problems the usual bay window doesn't have -- the vent AND the difference in the wall above and below the windows. Adding another post about that.

https://www.google.com/search?q=images+window+treatments&biw=837&bih=537&tbm=isch&tbo=u&source=univ&sa=X&sqi=2&ved=0ahUKEwim2KP48MDJAhWKPz4KHQQ9CLMQsAQIGw#tbm=isch&q=images+window+treatments+for+bay+windows

Since jalousie windows like yours are rarely draped, I doubt that possibility was ever considered in designing this window area and vents. A large custom fabric or roman shade that covers the entire window and is mounted high on the wall, can function when you want it to close and can be completely drawn up to act like a mock roman when you want it open. You could still add stationary panels at each end but they need to graze the floor.

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I strongly disagree with the suggestion someone made that drapes or window treatments by any name need to graze or drag on the floor -- that looks sloppy and is a dust catcher that will get in the way of cleaning. Then, too, I think thongs and spiked died hair are awful fads, too.

Drapes should hang from well above the window to well below the top of any baseboard but at least an inch above the flooring. But then opinions are like __ -- everyone has one.

A single straight window shade or drape hung from above the window would certainly work and likely be the best solution for the shape of these windows EXCEPT for reality that the vent does exist and would be blowing the drapes or any other long window treatment in front of and, therefore, BLOCKING the vent and that it would be trapping warmed and/or cooled air from the heat/ac unit in the space behind it when it is lowered.

If you're going to use shades and never lower them enough to encounter those two problems, at least consider that a valance alone would likely be less expensive.

http://www.stonehand.com/wp-content/uploads/2013/09/brownfrenchdoorcurtains11.jpg

http://blindbuilders.com/wp-content/uploads/2013/03/Moms-60th-0401.jpg

https://s-media-cache-ak0.pinimg.com/736x/d1/88/e9/d188e97dd9e7932db75c2231005b356d.jpg

http://www.baliblinds.com/BaliBlindsImages/ProductImages/drapery-swag.png

http://i5.walmartimages.com/dfw/dce07b8c-31db/k2-_5f8ae62d-4ff4-4b30-ae50-0d6edeb7afc9.v3.jpg

http://st.hzcdn.com/simgs/802117d603b31257_4-4569/transitional-curtain-rods.jpg

Isn't that an air return? Wouldn't the heat blow from the ceiling vent?

Merriam Webster says "graze" means to touch barely in passing, or to barely touch - we usually use the word "kiss" here on Houzz. The terms "break," "pool" and "puddle" usually apply to drapery that bends, gathers or falls out completely in a fan shape on the floor. See the following article for a bit more visual detail.

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Thanks all for the detailed input!!! The vents are heat vents (A/C comes from ceiling vents). We don't have a big need for privacy, our house sits up a bit and unless someone is standing right outside those windows, no one is looking it. The goal is more to give it a finished, warmer look (in keeping with modern aesthetic). If I do curtains, I agree with you, decoenthusiaste that they should be longer than the one that's there now. It looks a little silly to me. I think just hitting the floor (grazing i guess) would be ideal. Ultimately I think I will go with a shade...maybe with one heavy panel on each side for pizazz. Thanks all for feedback!!!