Sounds like you're thinking small. I would definately go bigger. I'll be adding onto my garage but it will be 24x24 for the shop space. I have about 17 planes and I seem to always be tinkering with one or five of them for any number of reasons. If this is going to be it, think out to the distant future also.
Edwin

I like those deep shelves near the ceiling I saw. Think I'll do that.