This is such a classic look and easy to achieve, especially for small spaces. Did you know that dark colors in a small room will blur the boundaries and look even bigger?!
We love this idea for a library or den, even a living room. It's simple, everything is painted out the same colour. Shelves, mantel on fireplace, walls, trim/doors.
2131-30 Lead Gray by Benjamin Moore, is a moody, midnight shade of deep grey that adds a layer of masculinity to a library or gentleman's study.

This high gloss look is very european and is so reflective that the colour will look even lighter in the space.

This dining room is sophisticated and laid back with it's rich blue walls and light drift wood furnishings.

No space suited for this deep moody blue, why not paint out some built shelves or free standing shelving unit?