My personal preference would be to arm the pilots and provide at least two plainclothed Sky Marshals. You'd know about the pilots, but the SMs would be the wild cards.
Ideally, the SMs would be trained to stay quiet and innocuous, and not be ID'd to the crew, yet somehow be assigned an aisle seat. They'd have to not look as if they just graduated from Parris Island. Any big-headed macho types running their mouths to impress female (or male, hey, I can be open-minded) flight attendants would be disciplined.
If I were plotting something using an airliner, the pilots being armed could be dealt with, but I would be put off by the one to three "wild cards" riding mixed in with the passengers.
Several of us were discussing the threats Al Queida made this past weekend against US and Jewish targets. We were thinking that the next attacks will be different; maybe on municipal water supplies with bio agents, or explosive-laden private planes crashed into nuclear power plants, or synchronized explosions on multiple subway trains in the same city. Taking out 20 subway or Metro trains at once would not be as dramatic as the WTC, but would have the terror effect.
Hope no BGs are reading.
Noah