AA Dining is a great way to rack up some easy miles, as previously mentioned.

You can get anywhere from 3 to 5 miles per dollar spent from this program. 3 miles per dollar at first, up to 5 miles per dollar after 15 dines and subsequent submitted reviews on the website. Dine count resets annually. Only rub is that sometimes the selection of participating restaurants isn't so great depending on your location. Those miles on top of the usual 1 for 1 earn rate from an AA credit card.

If you eat out once a week at a participating restaurant/bar, you can easily get to the top tier in short order.