The sofa must be larger than the area of the hanging picture. Thus when we choose the hanging picture, whether it is a piece or a group, the maximum width should not be greater than the width of the sofa to avoid apperaing top-heavy. 
The total length of the sofa is about 3.6 meters.
With 1 painting, the size of the banner hanging picture is "1.6 meters X 0.8 meters".
The size of the vertical hanging picture is "1 meter X 1.2 meters"
With 2 paintings, the hanging size is "0.7 meters X 0.9 meters"
With a combination painting, the size of the hanging picture should be within the range of "2.6 meters by 1.2 meters".
The total length of the sofa is about 2.6 meters.
With 1 painting, the size of the banner hanging picture is "1.2 meters X 0.6 meters".
The size of the vertical hanging picture is "0.8 meter X 1meters"
With 2 paintings, the hanging size is "0.6meters X 0.8 meters"
With a combination painting, the size of the hanging picture should be within the range of "2 meters by 1 meters".
The total length of the sofa is about 1.8meters.
With 1 painting, the size of the banner hanging picture is "1 meters X 0.5meters".
The size of the vertical hanging picture is "0.7meter X 0.9 meters"
With 2 paintings, the hanging size is "0.6meters X 0.8 meters"or"0.5meters X 0.5 meters"
The total length of the sofa is about 1.8meters.
