Actually, it depends on the situation. While some General officers believe the world revolves around them, there are a great number (majority, in fact) who know that they are riding on the tax-payer's dime. As such, they are ultra-sensitive about perceptions. Generals have lost their careers over misusing government aircraft for personal use; commercial travel really isn't any different.

Most Generals/Admirals fly enough that they have status with the major airlines. As such, they can use their miles for upgrades.

Loosely quoting the travel regulations, if one is booking a commercial trip that is longer than 12 hours (total duration) AND if there is a meeting/conference the following day, the government traveler is entitled to a business class fare. In reality, that does not happen too much, especially at the end of a fiscal year--Funds are tightly controlled.

Last year, my boss (Colonel) flew back to Japan from Bethesda after having neck surgery--a debilitating injury traced back to his days of college football. His command purchased a business class ticket--he was in tremendous pain. Later, an audit questioned the command's authorization for a business class fare. The Colonel immediately paid the difference out of his own pocket to avoid the appearance of unethical practice.

The last time I flew with a 2-star on NWA from KIX-HNL, he was op-upped immediately and had his name in bold print on the "special welcome" board. This was the exception rather than the rule. The travel office ensured that his record file indicated that he was a two-star Wing Commander.

While assigned to the department of defense several years back, we had to travel in uniform quite a bit. NEVER UNDER ANY CIRCUMSTANCES (while in uniform) were we to sit in anything other than coach. This was to avoid mis-perceptions and the fact that government contractors also travelled with us.

In short, I don't think there are too many General Officers who would step over the backs of their subordinates to get a seat up front. Most would never misuse finite funds to travel in the lap of luxury, knowing that they will be audited. Congress must also approve their promotions. So the bottom line is that the vast majority of Generals/Admirals who choose to sit up front are either doing it with their own miles or in accordance with government regulations.