Two configuration issues relevant for a new 200 seat aircraft have been addressed using a CIVIL multivariate optimisation code. Comparison of wide- and narrow-body configurations derived for the same mission shows the wide-body aircraft to have significantly increased direct operating costs, due to its increased mass and drag. Designs incorporating varying degrees of growth potential were developed. Significant growth potential was found to be possible with minimal operating cost penalty. However, the penalties increased rapidly for further increases in growth potential. Investigation of the performance of derivatives, based on one of these designs, showed negligible operating cost penalties relative to designs optimised for the same mission.