Delta SkyMiles and Northwest WorldPerks members can earn elite-qualifying miles plus double miles when staying two or more nights at any Hilton family hotel worldwide from July 15 through Oct. 15, 2009. Registration is required and you must select Delta SkyMiles or Northwest WorldPerks as your HHonors earning partner.

Members who earn variable miles will receive one bonus mile and one elite-qualifying mile for each dollar spent on a qualifying stay, up to a maximum of 5,000 elite-qualifying miles. Fixed miles members will earn 500 bonus miles and 500 elite-qualifying miles per stay. Visit http://www.HiltonHHonors.com/deltanorthwest