These Vanguard index funds provide cheap and easy exposure to international stocks.Morgan Stanley analysts led by Lisa Shalett expect the S&P 500 (^GSPC +0.88%) to return 6.3% annually over the next seven years. That would be substantially worse than the 15% annually we've had over the last seven years. But exceptionally high starting valuations are likely to be a major headwind in the future.Indeed, the S&P 500 currently trades at one of its most expensive cyclically adjusted price-to-earnings (CAPE) ratio ...