If it's that much, and in US dollars, the first thing to keep in mind is that you are/will be subject to US inheritance tax laws (both when you receive the money and again when you one day will it to your children if it's still in US funds). You should consult a specialized lawyer to plan around this.
You should also consider long term planning through trusts for many reasons (tax and otherwise), and will again need a different specialized lawyer.
Your investments should be dead simple and you should understand them completely: ie: broad market index ETFs. No hedge funds, options, swaps, futures, etc.
The advantage of big bank private banking is that they will put you in touch with a wide range of qualified professionals. You can get second opinions by setting up meetings with people from the "Big four" accounting firms (Deloitte, KPMG, E & Y, PWC).