I think the close relationship with Saudi Arabia is really more about oil than anything else. Saudi Arabia is probably the biggest financier of Muslim terrorism in the world, and yet is conspicuously missing from the US list of countries that fund terrorism (yet Cuba was on it until recently). Of course Saudi Arabia is also the world's largest producer of oil, and that's the primary reason why the US (and most of the oil consuming world, really) wants to be their friend. It is of course also why they have so much money to fund terrorism.