Most adults usually unpack their own clothes, clean up any of their spills and keep everything in control. Why would being kids be any different? The reasons you stated above that the room steward would be doing, along with cleaning the bathroom and vacuuming the floor are what he should be tipped for doing. That said, if you feel he hasn't earned the full tip, don't leave it. Think about how you would tip if you were all in the same room.