Through March 31, British Airways Executive Club members who convert Starwood Preferred Guest points into Executive Club miles will be able to do so at a 1:2 rate (one Starpoint converts to two BA miles), double the standard 1:1 conversion rate.

What’s more, British Airways will also double the standard 5,000-mile bonus Starwood awards when transferring in 20,000-point increments, meaning a transfer of 20,000 Starpoints, which would normally convert to 25,000 Executive Club miles, will now convert to 50,000 miles.

Executive Club has also teamed up with Marriott Rewards.

Through May 10, Marriott Rewards members can earn 25,000 Executive Club miles when transferring just 55,000 Marriott Rewards points — normally a transfer of 70,000 Rewards points would be required. Or, transfer 95,000 points to receive 50,000 miles (instead of the usual 125,000 points), enough for one World Traveler-class ticket from North America to London.

And, when members transfer points in higher quantities, they’ll not only end up with a great exchange rate, but they will also earn their choice of Marriott Rewards Travel packages. For example, a transfer of 185,000 Rewards points will result in 100,000 Executive Club miles (enough for two roundtrip World Traveler-class award tickets from North America to London) and a Marriott Rewards Travel package good for a weeklong stay at any category 1 though 5 Marriott Hotel. Or, transfer 242,500 Rewards points and receive 100,000 Executive Club miles and a weeklong “Anytime” stay at any category 1 through 5 Marriott hotel. And to top it off, members will receive a 25-percent discount on any Hertz rental while enjoying their vacation.

Packages that include stays in a category 6 or 7 Marriott hotel are available, but require more points.

For a complete list of available transfer options, visit http://www.marriottrewards.com.

Offer not valid for residents of Australia, New Zealand, Brazil, Argentina and Chile, Bhutan, Brunei, Burma, Cambodia, Guam, Hong Kong, Indonesia, China ( People’s Republic), Korea, Laos, Macao, Malaysia, Mongolia, Myanmar, Philippines, Singapore, Taiwan, Thailand and Vietnam.

Note to Starwood Preferred Guest and Marriott Rewards members: If you are not yet a British Airways Executive Club member, you won’t be able to just sign up to take advantage of these super offers, new members have restrictions — inquire.