Delta SkyMiles

How it works

SkyMiles is a fully dynamic, no-award-chart program whose value is mediocre on Delta metal but occasionally strong on partners during flash sales. Miles never expire and there are no fuel surcharges, but you'll usually get more value sending the underlying Amex points to Virgin Atlantic or Air France-KLM instead. Hold SkyMiles for the rare partner deal, not as a primary stash.

• Don't hoard SkyMiles — route transferable points to Virgin Atlantic or Flying Blue for better value.
• Miles never expire and there are no fuel surcharges — small consolations on a dynamic chart.
• Watch for flash 'SkyMiles deals' on partners and domestic routes.
• 1:1 from Amex US Membership Rewards, but usually a last resort.