Great contrast of stencil artwork- looks easy to do with stencil, paint, and canvas.
2 toned wall looks nice, adds texture to room
Contrast back color of bookshelf. Also, make bottom big enough to accommodate storage boxes or baskets of some sort for toys, etc.
Clothesline on contrasting ribbon to display cards, pictures, etc.
Artwork on wall - I could make simple design with paint or cutting out cloth,(wrap cloth around cardboard shapes to have nice tucked edges, and make the design layered).