I'm 1K on United, and the SWU certificates are the most valuable part of the program for me (I'm a US citizen living in London, so all my travel is international)

Beyond that, the upgrade mileage awards are the next most important. Every time a new timetable or newsletter/statement comes out, the first thing I check is the mileage required for the upgrade awards. I use my miles for a lot of family and friends to visit on free & upgrade tickets. If I were earning miles and intending to use an award in the future, but they upped the mileage requirement, I'd be on the phone asking for a grandfather-exemption for my plans. I have faith they'd do it.

Otherwise, the airlines ALWAYS cover themselves (in their terms & conditions)
- program rules may change without notice
- program may be suspended without notice

Thus, my philosophy is....
- there's a lot of competition out there
- I may change my loyalty without notice

Luckily, it hasn't come to that. My sister, who is also a 1K with United, has put it in words that I think capture it best, "Just when you're ready to run, they suck you back in." This came after the Summer From Hell.

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- Bob