We've wrestled with reader questions about this issue in the past but until we came accros //www.flickr.com/photos/hayesandjenn/153610676/">this photo on flickr we'd never considered one so simple and yet so striking: DIY fabric banners suspended from the wall or ceiling.
Hayes and Jenn make the bed canopy modern but boiling it down to its most basic element: two simple, solid-colored draped panels where a headboard would typically be stationed. They chose a color that complemented their bedding and used a metal curtain rod with what looks like O-rings and grommet holes. (West Elm's Steel Cable System would be even easier.) Reader Carley created a softer over-bed mount for her dangling origami crane chains by using eye screws in the ceiling and stringing picture wire between them.
There are infinite variations on the banner idea. You could drape panels from the ceiling and swoop them towards the walls. You could use fabric that's more diaphanous or more richly textured. You could use just one panel, or you could use many, each in a different color, to create a celebratory effect similar to Garnet Hill's ribbon shower curtain.
Or you could just keep it simple, like Hayes and Jenn did.