One reason for the CEOs and senior management to fly private jets is it's more productive. First, it allows them to work on the flight. Figuring 40 hours a week for 52 weeks, you only have 2,080 work hours a year. Take away holidays and vacation hours, and your talking less then 2,000 hours a year. If the CEO is making $20M a year and working 2,000 hours, he's making $10,000 an hour.
I work in the aeronautical Satcom (satellite communications) industry selling equipment to this companies which provides the capability for CEOs to communicate with their office while flying. By communicate I mean email, internet access and fax capability. So while the $10,000 an hour guy flies his private jet he's connected to his office in real-time, making decisions. He can even hold a video conference if he desires.
Also, when you fly your own jet you determine when you travel and are not at the mercy of the airlines. In the past 20 years, I've flown 2 million miles on commerical airliners. I've gotten stranded all over the world many times, and have spent a massive number of hours waiting on delayed flights.
When you fly your own luxury jet, your arrive at your destination rested and in a sharp mental state. If you're the CEO traveling to Japan to negotiate a big deal, not being at your sharpest will likelly cost you way more than the difference between flying commerical or private jet. I fly back from Toyko to DFW coach earlier this year and it took me two days to recover. I flew business class on the way from DFW to Tokyo. It was much more enjoyable, and I felt a hell of alot better after the flight. Some of the VIP aircraft I sell equipment for even have bedrooms, showers, etc.
Another thing to consider is the CEO doesn't usually go on a business trip alone. From my experience working with the flight departments of several major corporations, the average is 3-6 passengers on a flight. The GM G-IV holds 11-14 passengers. For such an important trip, probably every seat was full. So we're not talking about one commercial ticket; you're probably talking at least 10 first class airfares.
1990 7-up vert
2006 G35 6-MT Sedan