The design of slender wing, supersonic airliners has been considered from the viewpoint of obtaining maximum space utilization, A relationship between direct operating cost on trans-atlantic services and space utilization has been established, which shows, as might be expected, that the direct operating costs decrease as the utilization factor increases. A penalty associated with a high utility factor is a high wing loading. This leads to the necessity of using auxiliary lift when high utilization factors are obtained, It is shown that a propulsive engine modified to give jet lift at landing and possibly take-off is likely to be the best means of obtaining auxiliary lift. The optimum cruise height is less than that corresponding to maximum lift drag ratio because of the weight penalty associated with providing adequate thrust. The integrated layout is not suitable for airliners required to carry less than a hundred passengers, but becomes extremely attractive for a very large number of passengers In this case the central part of the wing area should be of constant depth with a cabin of side by side multi- bubble form. The delta planform is not ideal for an integrated layout, Better space utilization can be obtained using a pointed pear shaped Planform. Approximate calculations suggest that direct operating costs of a 120 seat airliner can be reduced by as much as 25% by using this type of layout.