Walls and Ceilings - Need ideas on how to make a wall without making a wall

The stairs to the second floor of my house go right up into the living room. The stair rail follows the stairs up then it makes a 180 and goes the width of the living room. I would like ot put the couches here but there is a child in the house who could climb on the couch and then fall over the rail. I need to build a wall here but i dont want to build a real wall for many reasons. It will make the size of the room seem smaller, it will not allow air to circulate and light from the stairs wont reach the living room. I thought about a PVC stlye wall but that would not allow airflow. Ideally a waterfall would be amazing but to get a 14'x8' water wall would cost a fortune. What other things can i do there to not mess up the look of the room and to prevent the child from falling over the railing?

The "wall" should be at least 38" higher than the back of any proposed furniture you plan to place there that a child could climb up on and fall over. Not seeing your situation, we can't give detailed information, only give some ideas. You may could restructure your balustrade to extend to the ceiling, ending on a decorative plate on top and bottom. Although it will give circulation, it may look to bar-ish. Building a knee wall and then extending the balustrade may look better, giving a solid base and safety in the extension.