With a large legacy carrier program like Delta's, members earn SkyMiles according to how far they fly, rather than to how many dollars they spend. And earning miles is easier because there are so many more partner companies, from FedEx to Fidelity, that offer ways to get bonus miles with everyday purchases.
Thinking of opening a brokerage account? That could get you 50,000 bonus miles -- enough for two free round trips.
SkyMiles is very much in line with the other major carriers' frequent flyer programs with one notable exception: Delta recently implemented a new policy eliminating its mileage expiration, so members can use their miles at any time. The change was effective for all accounts as of Jan. 1 of this year, propelling Delta to the front of the pack.
"Since Delta's miles no longer expire, they have the advantage," noted Tim Winship of FrequentFlier.com.
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