I read Kevin Phillips' 2004 book, American Dynasty: Aristocracy, Fortune, and the Politics of Deceit in the House of Bush and found it to be a good, straight-ahead account of how the Bushes have dedicated themselves to securing and enhancing the power of oil and financial interests.
Especially news to me was how Zapata Oil, in its early days, comprised dozens of spin-off front companies and was used by the CIA to spy on Cuba from its offshore platforms, which just happened to be the closest ones to Cuba. That definitely establishes an early relationship between GHW and CIA—and lends credence to claims that Bush was a CIA agent early on, the "Mr. George Bush" who appeared in JFK-related documents and the CIA later claimed was a different man, a mere "clerk."
One detail that intrigued me was the fact that grandad Prescott Bush, known for his love of singing, "revolutionized barbershop quartet harmony" at Yale.