Delta SkyMiles members who also participate in Hilton HHonors can earn Delta Medallion qualifying miles (MQMs) and double miles with stays of two consecutive nights or more at Hilton Worldwide hotels through Dec. 10, 2010. Registration is required before your stay at http://insideflyerus.wpengine.com/link/?2905 and you must select Delta Air Lines as your earning partner. If you select variable miles, you’ll earn one bonus mile plus one MQM for every $1 spent on a qualifying stay, up to 10,000 MQMs. Choose fixed miles and you’ll earn 500 bonus miles plus 500 MQMs per stay.

Bottom line: If you will be spending $500 or more on your stay, pick the variable miles option. Otherwise your earning will be capped at 500 bonus miles and 500 MQMs per stay. You can also change between fixed and variable miles to maximize your earning for each stay.