If your looking for a new living room look this one is great! Start with light grey colors and add one of your favorite colors to the room in pictures on the wall or as a desk, just to give it the calm vibe your looking for!
Rent a film projector and use a large screen (the back of a pool or just a strectched out sheet). Make the little cars out of cardboard boxes. Pop in a great kids movie. Serve popcorn and hot dogs and its a great time for all. The kids could even decorate their own cars as part of the party.