Wait, Wut? ETFs are bad because they can be sold intra day? Good Lawd, I have heard it all.
Not what I said, however ETFs were created to be bought and sold like stocks. So, it's easy to get sucked in to the temptation to buy and sell for some short-term cash. That's not how you build wealth for retirement. That's how you go broke.
Also, Most of retirement investing is done systematically through small, monthly contributions to a 401(k) or ROTH IRA. ETFs charge a broker's transaction fee each time you add money—that's in addition to the funds' normal operating fees. Those fees can quickly eat into your returns.
From the OP, I gathered he's not looking to be a trader or get involved in complicated investments, but rather a steady long term retirement investing approach.
But hey, to each his own.