It’s a summer tradition, just like in 2014 and in 2015, American will give you a 20% bonus for transferring Starwood points into AAdvantage miles through September 14.

20,000 Starwood points normally transfer to 25,000 American miles. With this bonus you’d get 30,000 American miles instead.

While the most obvious thing to do with Starwood points is use them for hotel stays, I think the most valuable thing to do with them is transfer them to airline miles.

That’s because:

• They transfer 1:1 into most airline programs (indeed, more airline transfer partners than Chase Ultimate Rewards or American Express Membership Rewards)
  
• You get 5000 bonus miles when you transfer points into 20,000 miles.

When transferred in 20,000 mile increments, you’re getting 1.25 airline miles per Starpoint with most transfer partners. That means a Starwood is worth at least 25% more than any of their airline partners. I consider them worth even more than that given their option value and their reputation as a store of value (they have less of a history of devaluations than most programs, although far from zero).

The downside is that points do not transfer instantly from Starwood to airline partners. In my experience Starwood transfers to American take 3-4 days. Fortunately American still lets you hold awards under most circumstances for 5 days, so you can lock in an award before making the transfer.

American will be adding that extra 20% within 7 days from the time the transfer posts to an American account. That means the extra bonus won’t show up in time to ticket award reservations held prior to making a transfer. So it’s more a play for future award booking, or for awards you’re confident will remain available, rather than one for locking in an award and then transferring.

American Boeing 787-8 Business Class

You never want to transfer more than 60,000 Starpoints to an airline in a day if you can avoid it. That’s because Starwood won’t post more than 79,999 miles to an airline in a day. 60,000 Starpoints posts 75,000 American miles (and then you’ll get 15,000 more American miles later with this promotion). By capping your transfers at 60,000 in a day, you maximize your 5000 mile bonuses for transferring points to miles.

If you want to transfer more than 60,000 Starpoints just split your transfer across multiple days.

I consider Starwood Starpoints the most valuable rewards currency and American miles are worth less than they used to be. So while a nice bonus if you were going to transfer points anyway, I’m not tempted to move any over just for this offer.