Make the window ends of the room the destination points. Place a decorative chair by each window, along with a table and a table lamp. Alternatively, place a desk and chair by each window. Symmetry is the key, however. Either of these options allows you to take advantage of the view from the windows.
Paint the walls of the room a bright, cheerful, light-colored shade like yellow, mint green or periwinkle blue. Light colors make the space seem airier. Dark colors make the space seem narrower and claustrophobic.
Place a long, low bookcase along one wall of the narrow room. Hang an enormous piece of art above it. Display books, statues and knick-knacks on the shelf. This makes the room feel like a living curio cabinet or an art gallery.
Place a framed mirror on the wall beside each window to reflect the natural light in the room and keep the room from feeling gloomy.