Before I forget let me respond about the price of oil bringing about unity in the U.S. The left, comprised in part by the Democrats and the MSM, want to bring about the destruction of this country as it now exists. We didn't even come together after 9/11. That is what Carl Rove's controversial speech was about. Even in the immediate aftermath of 9/11 the left was blaming the U.S. and siding with the terrorists. They took temporary refuge in silence because of public backlash but they did not change. They are still allies of the terrorists.
They do all they can to prevent our oil independence, from claiming a small portion of frozen tundra in Alaska to be a pristine wilderness area, to preventing their cherished windmill driven alternative energy from being built near their homes. They handicap our industrial strength through a myriad of laws, regulations, and lawsuits all backed by lie-filled propaganda.
The house of Faud(?), the present rulers in Saudi is comprised of so many wives with so many children who in turn have multiple wives and children that most of the ruling class is intertwined family members. With a tradition of Wahhabism they are sort of trapped in their own cocoon. They have to give lip service to Islam, though some family members really are radical fundamentalists, to keep the population quieted while they themselves live quite different lives.
With that in mind I suppose the answer to your question as to the value of Saudi to us, absent the oil, it would be to keep the lid on the radical fundamentalists in SA by keeping the present branch of the family in control. Even though the Wahhabis operate out of there, the present rulers are probably better than their replacements will be. Clamping down completely on the radicals would imperial the rulers themselves.
Any mideast country with great oil wealth, be it Iraq, Iran, Libya, Saudi, Kuwait, or whomever, who are outright and aggressive Islamists pose a grave threat to all civilization. We can't allow that even if we must stand alone in our vigil.