DV
If Bush's motivation was to wipe out the city of Fallujah, there are certainly more efficient ways to do it than sending in ground troops to fight house-to-house. If Bin Laden had the same capabilities, my guess is that he would employ them fully against any city in America, Spain, Britain, Canada, Jordan, or wherever else his infidel-radar tells him to strike.
Bush is certainly an inept blunderer, but to describe him as a willful genocidal maniac is a notion that is likely to find few sympathizers outside of the world of the Islamic extremists themselves.

I would say that, in the past, the US has certainly engaged in tactics that would fully deserve investigation, had it not ended the war as victor rather than vanquished. The fire bombings of Dresden and Tokyo during World War 2, as well as the detonation of the atomic bombs over Nagasaki and Hiroshima, could certainly be viewed as devastating and unjustified strikes against civilian targets. I believe that these attacks were basically designed to break the will of the enemy and lead to an early end to war, and were justified as reasonable responses to German and Japanese atrocities against Britain, China, and etc, although I personally believe them to be unjustifiable.