What hotels offer fully-refundable rooms? Most I ever see require cancellation the day before arrival (or at least by late afternoon the day of arrival). If hotels offered the equivalent of a refundable airline ticket (i.e. refundable at any time even after the scheduled date) I'd be all over it.

IMHO; hotels are worse than airlines at overselling because they don't offer this type of rate and they still overbook their rooms. Airlines at least have a plausible argument that they sell refundable tickets of which a certain percentage no-show and collect refunds after departure.