Personally, I'm on the 'she-shed' side. You could even build it in a way that you could take it with you if you were to move (like those tiny homes that are on the news a lot). No real stairs to deal with, but it would mean dealing with the winter weather. Hopefully you get less snow this year!
Here's a picture of my inspiration for what I want to build for a long-arm machine. I'll have to wait until my daughter is finished university (she's 4 now). But I can still dream...
http://www.fourlightshouses.com/blog...e-march-day-28