Dawn, have you ever seen the book Dream Sewing Spaces? I LOVE that book. It's been out for several years so I'm hoping it is "new" to you. See if you can get a copy from the library and start planning. :-) It has some very cool, clever ideas. What about a basement?
I haven't had a basement in 20 years and still have yet to figure out where people put their basement stuff, lol. :-)