The deal: Stay Longer, Pay Less discounts best flexible room rates up to 20% for those staying at least five days at one of 23 hotels in Europe, the Middle East and Asia. (Properties in France and Warsaw, Poland, require a seven-night stay.) You can get this deal online or by calling and asking for the summer offer.
When: The deal is good for travel from July 15-Sept. 22, based on availability. It must be booked at least seven days in advance.
Tested: I checked availability at the Intercontinental Berlin for Aug. 12-18. I found an average nightly rate, with the discount, of $143 a night instead of $204 a night. On the same nights, I found a room at the Intercontinental Budapest in Hungary for an average rate of $87 a night instead of $143 a night. (Prices are converted from euros and approximate.)