On both my recent hawaii trips I've gotten a small guarantee credit for monitoring my flights and claiming it when fares dropped close to departure. I monitor the OGG routes pretty closely as I have family in Hawaii, and this is something I've wondered about too. Sometimes you can find the lowest fare literally the day before a flight. I figure it might have something to be with it being a leisure destination but if that is the case, why doesn't a place such as LAS work that way too?