The first quarter 2012 promotions are slowly starting to be announced. Marriott just introduced theirs MegaMiles that runs from January 1st until April 30th. You can earn an additional 2000 miles per stay starting from your second stay. This promotion is based on stays and not on nights. Regardless how many nights your stay is, you will only earn the 2000 bonus miles.
There are 23 participating airlines. The miles for kilometers conversion will be 1 miles to 1.6 kilometers for those programs that use kilometers instead of miles. The airline partners are: