Sensory: Use soft foam tiles for a sensory room/area floor! The faux-wood can be more calming than loud colors and is also more "adult-looking" for a sensory room teens and adults will be using. http://www.foamtiles.com/tiles/38-soft-wood-tiles.html
Sew up some floor-length curtains and slide onto a dowel rod. Then hang dowel rods from basement rafters. Better than painting concrete (can lead to mold/mildew problems) and really softens the look of the basement.
It's hard to see but you can cover your ugly basement ceiling with cheap white fabric and a staple gun. I will post the before and after pictures when the whole room is complete. This will help perspective buyers not be creeped out and make the room feel crisp and clean with little effort and minimal cost.