Ever since I bought my mobile home at age 20, I've always needed about 1k SF just for me. Sad but true. My "little" house is 1200 SF basic ranch/starter house, 3 bedrooms, 1 bath. It was ok when it was just my son and me, but was way cramped when my husband moved in and son got to be an adult. I did manage to keep my guest/sewing room but it has a bunch of non-sewing stuff stored in the closet. I always planned to turn the converted garage into a long arm sewing room, but instead I have a husband (better deal than a sewing machine) and computer desks in here.
Son has moved out long ago, he and his now wife lived in a tiny Seattle studio for years, so I figure they must be well suited for each other, I never could have done it! They are expecting my first grandbaby any week now and will be welcoming it into their 1 bedroom apt -- about 570 SF.