I've always wondered why Marriott collects the # of guest and # of children info when I make reservations - I always blow by this when making reservations, even on the few times a year that the family comes along.

Since I'm paying by the room regardless of who's sleeping along with me, I've always felt this was an invasion of privacy. After all, Marriott goes to great lengths not notify you about property left behind, citing privacy concerns (see my thread about property left behind).

Outside of dining promotions (which seem to be limited to 2 people MAX anyway) or the risk of stuffing 10 people in one standard room, is there any other practical, operational insight why this collected?

If its Fire Marshall info or trying to gauge the strain on the infrastructure (hot water, maid service, restaurant usage), its pretty useless since its not uniformly collected, recorded and verified at check-in.