Earlier this year, the Vanguard S&P 500 ETF became the first exchange-traded fund (ETF) to surpass $1 trillion in assets. Continue »However, if given $1,000 to invest in any ETF in August, I'd choose the Vanguard Communication Services ETF (NYSEMKT: VOX) with its slightly higher 0.09% expense ratio, instead of the Vanguard S&P 500 ETF. Customizing ETF holdings with investment objectivesThe Vanguard S&P 500 ETF hit a new all-time closing high on Aug. 7, finishing the session at $710.71 per share. Or conversely, buy the Vanguard Morningstar Growth ETF or Vanguard Morningstar Mega Cap Growth ETF and support those holdings with individual, dividend-paying value stocks. That's why the Vanguard Communication Services ETF has a dirt cheap 17.1 price-to-earnings (P/E) ratio as of June 30 compared to a 27.5 P/E for the Vanguard S&P 500 ETF.