ggirl DS(5) has all his toys in his room - in theory at least - and his room is up lots of flights of stairs.
In some toy-related version of entropy, they do seem to migrate downstairs of their own accord but every so often I make him herd them all into a giant ikea bag to be lugged back upstairs - so the principle remains that they live in his room.
Unfortunately DD(20mths) is not old enough to be made/allowed to play in her room so the sitting room and kitchen are still covered in her toys
(as well as all our crap precious possessions and more crap important paperwork)