My room divider - 2 bookshelves, a tension rod, and two curtain panels. Definitely incorporating bookshelves, but maybe only a 4 foot high divider. Is less for privacy than creating a separate sleeping area in a "teen cave"
Convertible Furniture When you live in a small home. Convertible furniture makes it easy to switch from office to bedroom to dining area with just a few simple moves. Image courtesy of Matroshka Furniture