Since Peak Oil is upon us, why would you not want to fly for free around the world? This may be the last chance we regular folk have to fly commercial airlines on intercontinental flights. I would jump at the chance to fly all around the world on my company's dime.

Well I'd like to say it was because I was trying to conserve oil and reduce GHGs, but in reality it was being separated from the family that I was trying to avoid.
Plus the hassle of travelling (I got quite ill from jet-lag-induced sleep deprivation last time I travelled)...business trips rarely give much of a chance to do anything touristy.

Anyway, while I agree airline flights will significantly increase in price over the next few decades, they probably won't get much more expensive as a proportion of disposable income than they were, say, 30 years ago (trying to find some figures, but I'm willing to bet they were at least twice as expensive back then).