Those are tough shapes to do together for sure.

I think for me, I'd do a single rod, high on the wall to use a consistent treatment across all three maybe?


Or maybe make the rode level with the top of the side windows and leave the top arch window uncovered like this:

like the janine terstriep idea the best i think, with the rod going across the bottom of the arch and extending out beyond the 2 side windows....(but keep in mind that i am not a huge fan of valances, therefore i am somewhat biased) :)

In your photo, it looks like the top of the palladian window goes almost to the ceiling, and there also is a light there? So, it doesn't seem, in that case, that you could put a curtain rod up that high since you are going to run into the crown molding, so you should place it on the wall just outside the upper corners of the two side windows, like the others have suggested. Also, if you would like some covering for the arched one, here is a site you might be interested in.
http://www.the-window-treatment-expert.com/window_treatment_ideas.html

I just finished a dining room with this exact window. It is gorgeous!! One short rod on either side of the arched window and I used a woven nubby sheer. Let the window SHINE!! Please don't cut the window up by putting a rod under the arch. You can click on my picture to the left and take a look at the window under my projects . . Custom Traditional Home. Hope you decide to do something beautiful to enhance the architecture of the window. Cherry

I have the identical window configuration in my master bedroom. Had them done in plantation shutters (white) and the arch done in a fan shape plantation shutter. Really is beautiful. Open them in morning for sunshine and close tight at night for dark sleeping room. Considered drapes, but always looked complicated and took away from the clean look of this plantation window. Good luck.

Don't do a thing to this gorgeous window. Stunning as is. Forget rods, drapes, same ole, same ole flappery. If you need privacy, go for white cordless honeycomb shades that pull down when needed over 3 bottom sections--leave the top alone. They scrunch up unobtrusively when not in use--almost as tho not there.