IMHO, a unit doesn't need to be over 1,200 sq.ft. to be family friendly. I would say anything over 900 sq.ft. is enough for a family of three, provided the unit is laid out well. For example, my 1,050 sq.ft. unit would be a perfectly adequate 3/2+1 bedroom, 2 bathroom. But the lame floorplan makes it a cramped 2 bedroom (the living/dining room is stupidly large).
but they tend to be <1,200 sqft and poorly laid out