Through Dec. 15, 2014, earn up to 15,000 bonus United MileagePlus miles when you stay at one of five Marriott Hawaii Resorts. When you stay four consecutive nights, you’ll earn 10,000 bonus miles and when you stay five consecutive nights, you’ll earn 15,000 bonus miles. You will also receive a $50 dining credit at select resort restaurants.

To earn the bonus you must use the promotional code M12 when booking online at http://insideflyerus.wpengine.com/link/?11695 or when calling (800) 721-6996. Marriott Rewards members must select United MileagePlus as their earning preference in order to earn the bonus miles.

Participating hotels include Waikiki Beach Marriott Resort and Spa, JW Marriott Ihilani Ko Olina Resort and Spa, Kaua’i Marriott Resort, Waikoloa Beach Marriott Resort and Spa and Wailea Beach Marriott Resort and Spa. The offer is based on availability and advanced reservations are required.

Bottom line: Do the math before signing up to decide if this is the deal for you. Our research found that the promotional rate allowing you to earn the bonus miles and the dining credit can be about $30 per night higher (varies depending on hotel, date, room) than the lowest standard rate (when the M12 rate was available, which is not all of the time). So for a four-night stay, your cost would be $120 more than the lowest standard rate for the same room category. Minus the $50 dining credit, that’s $70, which is the equivalent of paying .007 per mile.