If like me you're trying to make some sense of this market, I found
this piece by Schwab analyst Liz Sonders quite interesting.
As you'd expect from an analyst at a brokerage, she doesn't give a straight answer, but I found the list of what a number of common valuation metrics indicate (about halfway down) very informative. I don't think there are any surprises (tl;dr, market seems expensive, but with interest rates at zero, it actually may not be) but it helped me structure my thinking a little.
