When Nell Williams was the director of revenue management responsible for the 400-room Long Wharf Marriott in Boston, there were certain days of the week—Wednesdays, Thursdays and Saturdays—when she could easily sell out the hotel twice over. But on other nights, like Sundays, occupancy rates dipped so dramatically that she would've been lucky to have filled the rooms three times a year. Both situations presented challenges for Williams, whose job was not just to sell rooms but to sell them in such a way that would make the most money for the hotel. She used a combination of pricing and inventory controls to maximize profits. On the high-demand nights, she had to be careful not to sell out early at low rates. She also had to consider lengths of stay. There were plenty of business travelers wanting to stay one night and willing to pay top dollar. But those customers would not help her fill the hotel on less busy days the way a three-night stay might. Meanwhile, on Sundays, she needed enough rooms available at the lower rates to attract customers, but not so many that she might give rooms away to someone willing to pay more.