My girlfriend, daughter and I are quite comfortable in 700 square feet. More would obviously be nice, but neither one of us are willing to move to the parts of town necessary to make that affordable. When I was on my own I lived in a 450 sq ft apartment which I considered plenty big enough for me, and where I (god forbid) ever to find myself alone again I'd probably move back to a 400-500 sq foot apartment. Again bigger would be nice, but not nice enough to sacrifice either location or the extra money.