Paint the room a warm color like a mocha or coffee tone. Color can change the appearance of an unusually long, narrow room.
Draw the eye upward by painting the ceiling a light color. Use bright white or cream-colored paint.
Define seating areas by using area rugs to decorate. Place rugs on the angle to fool the eye into thinking the space is wider and place furniture accordingly.
Capitalize on the fireplace by using it as a major focal point and place a large, comfortable sofa perpendicular to the fireplace with two chairs opposite the sofa next to the fireplace.
Mount a mirror horizontally rather than vertically to use reflection to fool the eye into thinking the room is wider. Mount the mirror on a side wall, not an end wall to create better balance.
Put a smaller seating area on the opposite wall from the sofa further down the room. Then use a small side table and chairs on the wall across from it to balance the room.
Achieve balance and cohesiveness by incorporating the dominate colors of the upholstered furniture in the room accessories. Decorate with several complementary fabrics in solids, patterns and stripes and make throw pillows to mix and match in each seating area of the room.
Add a few large plants with small, hidden "up lights" to decorate and draw the eye upward creating the illusion of spaciousness. Also, use several torché floor lamps to continue the illusion in the room.