Thanks again for all the replies. Since this is all kind of foriegn to me I am considering all my options. I have room of 20 or 24' wide so that works good. I do like the idea of a steel building just for the perceived lack of maintenance and what I understand is a much lower price....could be wrong on that.
Since I have no skills working with anything wood, I will have to hire it done.
Plenty of references to a "pole" barn but I'm not clear on what that is exactly. I'm not sure I care as long as it's enclosed.
The floor is an open question. Concrete is nice but there are probably other option including gravel or just leave it typical AZ hard pan with railroad tie pads like I'm currently using.
Thanks again for the input, great and useful comments.