Is that a house or an light industrial factory unit with domestic pretensions?
Seriously, why would you need that much space? After putting in the 40th bedroom it would get v. boring. I'd have to start making up new uses for rooms;
(1) One childs playroom for each day of the week - with duplicate sets of toys (that way each toy room gets trashed once a week instead of daily).
(2) Live-in quarters for the in-laws, and their in-laws, and their inlaws... (actually scratch that one, I actually gagged at the thought of living with them).
(3) Pre-screening / cleaning room for car, dog, children, etc. - ensure that ALL the muck that is carried on them stays out (may come in handy in a few years when my daughters start dating).
Anybody have any others?
Jim.