I took a look at the panels on the bedbathstore site.
Those would probably work well. You'll probably need at least 4 panels, 2 on each side. Depending on how it looks, you'll want to either leave them separate or seam them together to make a wider panel so there will be enough fullness to give a decorative fold to the material when hung on a rod.
Is 120 inches long enough to cover the full height of both windows or will you need to join two panels together and hem them to the correct length?