Choose a wall color that will make your sofa stand out. Darker sofa colors can be complimented with lighter, but exuberant colors. Cream or lighter colored sofa can be blended with darker colored walls.
Lay down an area rug in the center of the room. Pick colors that coordinate with the sofa's solid color. Decorate the room with a nice, patterned area rug -- not too big, however, because you don't want it to overwhelm the simplistic style of your leather sofa.
Purchase end tables that match closely with the leather furniture. If you leather sofa has dark colored wood legs, pick corner end tables that match the wood of the sofa legs.
Pair a few leather ottomans to some of the sofa cushions if your living room has enough space. These can be used instead of a coffee table. If you already have end tables, you may want ottomans instead. They are more practical.
Curtains with patterns can compliment the walls and stand out with all the solids colors in your room. Follow the same color scheme with the patterns and curtains. As long as the colors match with the sofas, the curtains will look good in the room.