Since your pictures are oriented both ways what about adding borders to your blocks to make them all 12X12" finished in one of his favourite colours and then adding sashing in a theme fabric of somehting he enjoys (it could be anything-sports, animals, food, etc) and then using your border fabric again to border it and bind with theme fabric. This is just an idea to help make it so that your sashing is broken up and doesn't seem to over power the pictures. Whatever you come up with he is going to love his quilt.