We could have invaded Saudi Arabia after 9/11 instead of Iraq, but then there is that whole Mecca thing......which is kind of a complicated problem, I think you would agree. And, since they serve as a foil to Iran, it is an even more complicated problem.
They are a conundrum as far as US policy is concerned. They are an evil society...the radical Wahabian faith led to 9/11, and yet you want more Wahabians in the United States, while at the same time you want to punish the regime which regulates those Wahabians and cooperates with the US.