Actually for neither. The US wants a democracy in the middle east that is supportive of the western world (not just tolerant like the Saudi govornment) so that they can keep an eye on things like nuclear technology that is going on in the middle east. A 747 has shown that it can do quite a bit of damage, but look at the death and damage the atomic bomb did on Hiroshima and Nagasaki. There are nuclear weapons that are hundreds of times more powerful than those now.
I do not like war, never have, never will. I don't like American soldiers, nor Iraqi citiczens losing their lives, but there is a bigger picture than just some scattered about terrorist group OR crude oil supplies. I realize the US government looks like a bunch of bullies to many (including a great deal of US citizens) but President Bush stated from the very beginning that the war in Iraq was for "stability" in the middle east. Those countries have been fighting themselves, each other and Isreal for decades. The combination of that with the nuclear technology that has now been reaching the mid-east, and that is the baseline for this war..... to stop a nuclear attack on Israel or another Mid-East country. Bush has never said that in so many words so that there is no panic, but that is reality.
In those oil producing nations, you have very little middle class outside of the metropolis cities. You have the rich and the poor. You also have deeply religious people that are not well educated and can be swayed by misinterpretations of their religion. That is a bad mixture.
Bryant