not pretty but it is clever. Vertebrae by Paul Hernon of Design Odyssey Ltd - Vertebrae packs a toilet, sink, two shower modules (one for children), storage space for shower, bath, shaving, and cosmetic products right along the column. Each component is a swingable module that can be used when needed. (more space saving furniture: http://www.home-designing.com/2008/10/space-saving-furniture# )
Love those birds, such a cute design! Looks like a nice sturdy toy box too! Toy Box - Bird Cherry Red/Pink, Girls Toy Box, Toy Chest, Toy Storage, Toy Bin, Wooden Box, Child's Toy Chest, Childrens Furniture, Storage
Pull out Wardrobe Rail for under stairs. You could have a few of these attached under the higher stairs and some storage boxes or even a chest of drawers underneath, then you could do away with the black frame and the room would look / be much larger.