How Hotel Reservations Work 
Hotel yield management is about a decade or so behind the airlines, but they're catching up, so this is probably going to get a bit harder from the OTA's/customer's perspectives before it gets easier.  (Yield management means the art/science of room pricing such that you sell out nearly all of your inventory while maximizing profits.  It has gotten radically more sophisticated over the years -- loyalty programs, for example, are only about 30 years old, and they virtually transformed the industry.  (They're patterned off of airline mileage programs, which debuted in 1979.)<p>This is, by the way, one of those boring fields where people who look like programmers, talk like programmers, and act like programmers take home bonuses like bank presidents.  (Interview question: "To within an order of magnitude, how much money does it make Marriott if we increase systemwide occupancy rates by 5 basis points this year?")