We're big fans of pocket and sliding doors, which allow a space to be sectioned off without blocking circulation, air flow, and views when you need them. If you're looking for a way to enclose a bedroom in a loft or open plan apartment, dividers like these can be really useful.
Shown above are examples from around the world—Spain, Sweden, Japan, and the U.S. Possibilities range from traditional pocket doors (which slide in an out of a gap in the wall) and custom-fitted sliding doors in opaque, slatted, or translucent materials. For other ideas and resources, check the links at the bottom of this post.
Photos: Destination BCN (1,4,5), Jill Slater (2,3), Innerspec (6), Aaron Able (7,8,9,10)