This is where we might add an extension, to provide a family room, study, eating nook etc. downstairs. And upstairs, allowing a master bedroom and bath, closet space etc. (It doesn't need to be big as long as it is functional and comfortable).

Note that presently there is a septic tank in this yard (about 20 feet from the house toward the front end). Then again, there's no leaching field, so we need to do septic work anyway, might as well move it if neeeded.