This is part of Reason's 2025 summer travel issue. Click here to read the rest of the issue. I joined my first frequent flyer program—American AAdvantage—before a trip to Australia in 1991. Sadly, I let those miles expire. Five years later I was out of college, flying regularly for work, and reading all the materials airlines used to send in the mail. Poring over the terms and conditions, I saw where I could earn 5,000 MileagePlus miles for buying four sodas in four different restaurants. I pick...