Build a 2 story shed. Buddy built one where the footprint was inside the by-lays. The 2nd story though was bigger...think mushroom shape.
I went with a prefabricated composite shed this time. It was easy to put up and seems to be quite durable. Also aesthetically it kept the wife happy as she doesn't like the wooden sheds. If I have to do it over again I will definitely consider building one with an upper storage area.