When life revolves around play (I mean learning!) it's difficult to pinpoint the central hub of fun. It might be Jack's room.
Luke, for one, would agree his brother's room is super awesome. But, there is always something to protest about: the green car is out of reach, the drum wont play the right music, or he needs you to get off your lazy butt and turn the robot on.
Jack just goes with the flow even if a little batty.