I believe 9/11 was an inside job now

[Fidel_Castronaut]

Or, alternatively, they could have just detonated lots of bombs around NY. Same effect, maybe even the same casualties, but arguably a lot less planning required.

Exactly. Just plant and set off a few bombs in different places, perhaps in front of different important or well-known buildings, then round up a few Muslims holding anti-US sentiments, then claim they're members of al-Qaida, and invent evidence linking them to the bombings. Claim that there's a massive a-Q conspiracy to attack different cities across the country, declare a war on terror and start invading the Middle East. Much simpler and easier than an incredibly complicated 9/11 scenario which may or may not even work as planned.

And frankly, if 9/11 were an inside job, what's to gain by crashing an aircraft in a field in Pennsylvania?

What about a dirty bomb? Something small but with high fear impact? That would have taken literally no planning at all considering how many materials/resources the US govt. presumably already has.

Invent a story about radicals getting their hands on it (include Russia to re-kindle old patriotic values from the right), and gaining access to the states to detonate it (or, even better, make them internal terrorists, which would have the same net effect of increasing the mandate of surveillance if that was indeed the ultimate goal).

This would also double the mandate for ensuring the elimination of WMDs further down the line.

Man, I should totally be involved in this! I'd be a super star at instigating international conflicts. If you're watching Obama, put me on the team, I'm ready coach.