I like when everything cleans up easily, it's easy for the kids to help, and it doesn't look cluttered. That's not to much to ask right? My newest project is a shelving system from ikea, super affordable and can be rearranged easily. My playroom is yellow and gray, and I put the shelving system on the yellow wall, to tone it down a bit.
So far the only part that is done is the puzzles. I ditched all the puzzle boxes, bought some containers from ikea and taped pictures of the puzzle onto the lid. Now they're easy to stack, the kids can get them by themselves (and clean them up by themselves! ) and it looks so nice.