George W. Bush looked like a prize fool on 9/11. The speech he made was stiff, wooden, stupid and uninspiring. He stood staring at the camera as if he couldn't really believe it was happening.
When he got the news, he sat staring at "My Pet Goat" as though waiting for someone to tell him what to do.
Now, if the hijackings had been a government conspiracy, don't you think they'd have tried to make the president look a little more heroic. Imagine having him get the news on an airforce base, or while standing in Independence Hall, or at the Old North Church in Boston. Or they could have put him in the oval office, and told him to refuse to leave.
But the hero of the day was Rudi Giuliani, not Bush.
If you are going to crash a plane on purpose, you're best bet is to do it over the ocean or a river, like the Monongahela, which is large, deep, and muddy, so things disappear there all the time.
You would not crash it in a popular tourist area, like Somerset Pennsylvania, where people will be prowling the crash site with metal detectors for decades.