This article has some good ideas too. :
Two story great room windows
Having two story rooms in your home, complete with two story widows makes for a very dramatic effect, but having 18 vertical feet of windows can cause a huge dilemma when it comes to dressing them. Having custom window treatments made for your window is usually the most obvious option. Of course, it can be cost prohibitive. Here are some ideas you can use to make treatments for these awesome windows on your own.
You can purchase window scarves in 6-yard lengths and instead of using these as window scarves, you can hang them on a pole and use as a window panel instead. These panels are available in sheer, silks, and velvets among other fabrics. If you normally use one window panel for a window, in this case you would want to use two because these panels are not as wide. Because the window treatment is two stories long, you will want to add jewels, beaded trim, or weights at the bottom to keep them from blowing into the room.
If you cannot find the right scarves to convert into your window panels, you can purchase fabric and sew them yourself. You will need six yards and a few inches for each window panel, and you will want to add lining to many fabrics to prevent fading. All you need to do is measure the length of your fabric and sew the hem and the header. If the fabric does not have attractive side seams, you will need to sew them as well. It would probably be best to avoid fabrics where the sides would need to be sewn.
You can make gradient light curtains panels from a series or coordinating window panels. For example, purchase a normal 6-foot sheer window panel, a 6-foot silk window panel and a 6-foot velvet window panel. Be sure all of the panels are of the same color or coordinate well. Then sew the top of the silk panel to the bottom of the sheer panel, and then sew the top of the velvet panel the bottom of the silk panel. The effect will allow you to have light a lot of light filtering through the top of your panel, a little light coming through the center and maximum privacy in the bottom section. Be sure to remove the hem and header sections before attaching the panels. In the same way, you can make panels out of different color curtains of the same weight of style. For example, you can make a sheer curtain that starts cream colored, the middle section is gold, and the bottom section is green.
In hanging your two story window treatments, you can choose to have them cover the windows or you can hang the panels between the windows to accent them. If you need curtains you can open and close, you best option is to make full window treatments and use tiebacks at the bottom because you will not be able to reach the pole to adjust the treatment.
In making toppers for these windows, cornice boards should be close to the window or you will be able to see the underside when looking up. Fabric window toppers with very large tassels (because they are so far away) work nicely as well.