What are these perks? I assumed things like nicer waiting rooms at airports, which always struck me as like having cleaner cells in prison.
* Free (capacity-based) upgrades to first class on domestic flights
* Buying a full-fare economy-class (rather than discounted) ticket auto-upgrades you to first class at time of purchase
* Free checked bags
* Free access to exit rows and other extra-legroom seats
* Discount on lounge membership, and free access to lounges when you're departing internationally
* Priority customer-service access
* Waiving of lots of fees (for things like last-minute flight changes)
Moving up through the status levels, the perks have a tendency to get pretty nice; I've done multiple flights to/from Europe where I paid for an economy-class ticket and upgraded into business class for free, for example. I've also had access, regardless of fare class, to the fancy international lounges (most recently, had a shower and a hot breakfast after an overnight flight into London a couple weeks ago).
Also slightly related: nobody pays for first class on domestic flights. Everyone up in first class is normally a frequent flyer (they tell you when you check in if you got an upgrade).
Also, on the big three carriers (America, Delta and United), upgrades get processed multiple days out depending on your level of status. Currently as Executive Platinum on AA, I can be upgraded as early as four days out from the flight. I'm actually waiting for the email right now to see if my upgrades will clear for a couple segments later this week.
I'd be happy to go to prison if it meant I got free massages in a spa[1] or chauffeured around in a Porsche[2].
[1] http://travelsort.com/blog/thai-airways-first-class-lounge-a...
[2] http://upgrd.com/regionalfirst/the-best-lounge-in-the-world-...