Received an email from Delta offering double miles if I opt to travel at a higher fare class. Here is the relevant portion of the of the offer:

Here’s your chance to travel in style—and get rewarded in the process. Book a higher fare class on your next round-trip Delta or Northwest flight and you’ll earn double miles. Register for this offer, then book and complete your round-trip flight by September 7, 2009 to land the double miles.

You can even get double miles for moving to the higher Economy classes. But you have to register, book and complete travel by September 7, 2009 to get the double miles. Hey, this may open up a new way of flying for you. Book your Delta or Northwest flights today.

Here is a breakdown of the bonuses: