Jim, I don't think anybody would ridicule you out of here if you have a cramped or messy shop. You should see my dad's shop. Now THAT'S a mess, and it's huge. 12x25 or so, and there's not even a trail on the floor you can walk on. It's just FILLED with junk. He's got all the good power tools, too. Drill press, floor band saw, table saw, sliding miter saw, table planer, routers, all sorts of cool stuff, and you couldn't use it if your life depended on it. But then he hasn't used his shop in 28 years, not since he chopped his pinky finger off when he made a little rocking chair for me.
As far as big enough, I have exactly enough free floor space (if you put the stools outside) to put one 4x8 sheet of ply down to cut, with a tiny path around it. I'd rather cut wood out in the drive way though.