Upgrades?

[Tim B]

On a recent flight to Auckland with Emirates, I booked the economy ticket for around $250 one way, and during the week before I was due to fly, I received an email from Emirates asking if I would like to upgrade to Business for an extra $250. Tempting as it was, a window seat in economy in an A380 is roomy enough.
On the return flight on an AirNZ B767 (like a cattle truck compared to the A380), I also received an email from AirNZ just before I was due fly, asking if I wanted to upgrade to business class, but the amount was "name your price", and I suppose they think if its a reasonable enough price, they will accept it.
I'm sure both airlines only do this if they know they will have empty seats. The AirNZ flight was only about 2/3 full.