Wow. Nothing I know of that is guaranteed. However, if I had that much to work with, I would seek out a competent (fee-based) financial advisor for guidance. I would study up on Warren Buffet if you haven't already done so. Finally, there are a variety of tax shelters out there that can help. IRA is an example for people with *cough* much lower assets to work with, such as myself.
Again, studying Warren Buffet might help. He was famously noted for having paid lower in taxes than his secretary.
Good luck. Wish I had your dilemma.
