DIVERSIFY YOUR HUE It's a common pitfall.  You want a blue (or green or yellow or red) room and you think the answer is paint.   But alas, a room is not built on paint alone.  A room with one color is like a song with one note – flat.  It takes layers of colors, textures, fabrics and finishes to really make a room "sing".  The dining room below from Bunny Williams is a beautiful example.  The star of this room is a dramatic cerulean blue, but it's the supporting shades of green, yellow, gold and cream that make it pop.  Moreover, the designer chose checked slipcovers, a large 18th…