GumbyChuck said:Small enough you can machine stuff in your closet.
Not big enough for most things.
Having run my own machine shop, whatever size lathe you get, thinking it will be big enough, won't be. There's always the next job just a little too big to fit your equipment without some creativity.
That being said, a 12x36 will do most motorcycle work, gunsmith work, etc. Good size for the serious home shop. Lots of work still gets done on 9" southbend lathes, too.
I've got an 11" Clausing in my shop that does everything I need nowadays.