Had this happen twice in recent months: once in Sydney when we got upgraded to a king on the executive floor, once at a Canadian Hilton where we were upgraded on arrival into a large suite with one king bed. In both cases we'd explicitly specified our need for a room with two queen / double beds (as we were traveling with large teenage son) in the reservation notes, which were overlooked / ignored both times. Large teenage son doesn't do rollaways... and why should he? He's on vacation at a nice hotel, not camping. At check-in I asked to be downgraded to the room originally booked and the clerks complied without a hitch. It's totally OK to refuse a downgrade. Most of the time the hotel is simply trying to be nice when it upgrades you, but it drives me crazy when they ignore your booking requirements in the process.