Instead of a giant curtain rod
Curtain hardware can be expensive, especially if you have a very large bank of windows requiring and extra long rod. I recently did a consultation with a woman with exactly this issue. Her apartment has a lovely bank of windows looking out into the trees, making it feel a bit like living in a treehouse (and who doesn't love that?)
While the room needed softening, the windows did not need functional panels. Instead of shelling out for a jumbo rod, I suggested that she buy two smaller, less expensive ones instead.
(The more I pair "rod" with various synonyms for "large," the dirtier it sounds.)
I happened upon this photo from a Sneak Peek on Designsponge that shows the prettiest way to do this.
The key here is that the curtain does not completely fill the rod. That extra foot or so gives it all a little breathing room. Plus, making sure the rod is visible makes certain that your curtains don't look like they are growing out of your ceiling.
Of course, if you want a seamless, rod-free look (and a truly stationery curtain), mount the top of the treatment to a block of wood, and drill it to the wall.
Easy, pretty panels!