You could make two quilts, one sister gets winter/spring, another gets summer/fall. Then add decorative borders around each set of panels to make 'em big enough.
Or, you could do one panel for the front with decorative borders, and have one in the back with large plain borders. That way it's kindof double-sided. That's what I'd probably do, and make two of those... even though it's lots more work. But maybe you could make drag-around "blankie" sized quilts instead of something big enough for a bed.