50% Amex Transfer Bonus to Starwood Until March 31, 2012!

Update: Some offers mentioned below are no longer available. View the current offers here.

Offer expired on March 31, 2012.

Starwood Preferred Guest is a transfer partner of American Express, but the normal transfer ratio is a dismal 3:1, which means you'd need to transfer 60,000 Amex to get 20,000 SPG (which can then be transferred on to a number of airlines at a 25% bonus).

However, until March 31, 2012 Amex is running a 2:1 ratio, which is better but still not amazing. The bonus is hard-coded into the transfer ratio, so no need to register and the points should transfer automatically. Just log-in to Membershiprewards.com -> Use points -> Hotels and then Starwood along the side of the screen or click here.

I see two main reasons people might take advantage of this (but feel free to comment on why it might make sense for you):

1) To build American Airlines miles. Currently AA is not a member of either of the main transferable points programs, Amex Membership Rewards or Chase Ultimate Rewards, so you can essentially transfer points to Starwood at 40,000 Amex to 20,000 SPG and then transfer to AA at the 25% bonus and end up with 25,000 American Airlines miles. If you are swimming in Amex points and want to redeem for a great AA award (like 40,000 miles offpeak coach roundtrip to Europe), this could make sense, but it's still a 1: .625 transfer ratio of Amex to AA. Check out this post for more on maximizing AA awards.

2) To take advantage of one of my favorite point redemption methods, Starwood Cash & Points. I can often get over 4 cents per Starpoint in value when I redeem for Cash & Points stays, so if you value Starpoints at more than two times Amex points, this transfer bonus might make sense. Plus, Cash & Point and award stays now count towards SPG elite status and starting today Starwood is adding a ton of benefits to Gold and Platinum status.

Hat tip TPG reader Scott!