With this much money you obviously don't want to be dropping the whole lot into the market at one point. If this were 2009 it would've been a great decision, but after a 2-year bull run that looks like it's petering out I'd probably opt to keep most of it in cash/bonds/money market until you have a better plan for the money.
Perhaps over a 3-year span. However, over 10-20 years, you can't beat the market. Even if you try to predict the ups and downs, the odds are pretty stacked against you. The only funds that have been able to beat the market over a non-trivial span of time have been pyramid schemes.
