Your best bet is to select a combination of options that suits your own situation - your age, when you expect to retire, your ability to sleep when markets are in turmoil. If you're young, for example, you can generally afford more risk and may emphasize stocks in your allocation. History is on your side. The closer you are to retirement, the more disastrous a knee-jerk investment decision turned sour can be for you. Instead of moving in and out of the market, investors who remained invested for the entire period achieved higher returns for each holding period.
Past performance is no guarantee of future results.