First off, I absolutely LOVE the YELLOW pantry door, Secondly, I love the idea of a pocket door. It is saves space because it slides from side-to-side without compromising the space it would take to open a regular door.
Make the outside of the indoor "playhouse/room" to look like a real house. I would only of dreamt to have something like this as a kid. My kiddo and future kiddos deserve a kickass room they would be proud of.