I'm seconding FflyinMike:
1. Ability to bend/break most of the rules, most of the time, and not pay change fees, ever. I must have been "gifted" $2,000 last year in saved fees
2. Many unexpected good things happening, too many to get into...
3. Operational upgrades and uncollected certs
4. Exit row advance seating when I don't want to sit up front.
5. Pleather, that one time...