The best thing you can do right now is taking a good 3-6 months to figure out what you want to do with this money, framed in terms of what you want to do in your life. Just park the money in a safe place (eg money market fund, treasury bills) and work things out. There's no need to rush into things, the money will still be there when you know what you want to accomplish with it.

After you've done that, you should have some idea of when/whether you plan to use the money, and how comfortable you are with losing some of it. To be honest, you're probably best off just choosing a reasonable mix of stocks/bonds/cash which reflects your goals/needs, then going on with your life. 5mil sounds like a lot, but in investment-land it's not an unusual amount for a family to have saved for retirement. You would be well off to check out the Bogleheads wiki and forum at http://bogleheads.org. The forum would be an excellent place to post any questions you may have.

With regard to specific allocations, here are some example mixes between stocks and bonds, and how those behaved over 40 years. It's not the best chart, but it should give you some idea. Note that the author is subtracting out an annual 1% management fee from those returns, which is completely bogus. Go with good index funds and you'll be paying 1/15th of that. http://www.fundadvice.com/images/stories/fundadvice_images/f...

Also, if you ultimately decide that you really want to get into real estate, you might want to consider REIT mutual funds/ETFs, rather than buying individual real estate properties and the risk/maintenance that comes with them.