(all planes hit, GWB killed)
Cheney becomes president, and the unity mood probably gets a hawkish Democrat (Lieberman or Joe Biden most likely at this juncture) in the VP slot. Cheney really is harsher than Bush, and the nation probably isn't in a mood for nonsense: the scenario that only narrowly got shot down OTL is instead implemented.
It is not well known, but several allied and neutral powers (Russia, France, etc) greenlighted limited nuclear retaliation. Britain was not in favor, and Bush valued Blair's opinion enough to deepsix the idea. Here, the plan goes forward, with Al-Qaeda members getting a thermonuclear tan. Afghanistan is invaded and occupied as OTL, but the Iraq war doesn't happen - Saddam does what Ghadaffi did OTL and lets the US look at/investigate/whatever to its heart's content, rather than risk pissing off an America with a proven willingness to hit the button.