Many years ago I put my parents in some great American Funds (Washington Moo, Cap Income Bldrs, Fundamental Investors). They had a great retirement.
But Spy (which wasn't around then) beats the tar out of all of them.
I use SPY as my foundation...and spread out from there.
I look at SPY as my little fishing pier. I stand on the end of it and cast for higher returns. When the skies turn ugly, I pull everything back into SPY.
I live simply...so that if the market takes a dive, I will wait until it recovers.
Spiders/SPDR (NYSE:SPY) is the largest ETF, with net assets of $173 billion. With an expense ratio of only 0.095%, SPYs are a natural core equity holding for all investors. It has none of the negative characteristics of the other ETF types that I mentioned above.