If it is for stays between May 17 and September 30, that doesn't explain the the rates in December being discounted!
I see this page:
Hilton Worldwide - The Great Getaway
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[TD="class: bodyCopy"] Take some well-deserved time off with The Great Getaway. Save up to 40% when you book by August 1, 2012 and stay by December 30, 2012 at participating hotels and resorts in the Hilton Worldwide portfolio. With a room for every budget and any occasion, your next getaway is our top-priority – you've earned it.[/TD]
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