Frequent Flyer Credit Cards vs. Cash Back Cards
If you earn most of your frequent flyer miles with an airline-affiliated credit card, but that the miles you earn are getting harder to spend on free travel, then maybe it's time to consider a cash-back credit card instead. Many credit card issuers and banks offer them, and in some cases you can earn up to 2 percent cash back on everything you charge.
Doing a little math, you can see that spending $10,000 on an airline-affiliated credit card will earn you just 10,000 miles, not enough to fly anywhere. But the same $10,000 on a Capital One or Fidelity 2% cash back card with earn you $200, which you can spend on an airfare (or on anything for that matter).
There are no capacity controls on cash, as there are on frequent flyer award seats.
There are no fees for spending your cash on an airline fare.