When you're a long-term investor saving and investing for retirement, it's hard to beat the simplicity and power of a low-fee, broad-market index fund such as one that tracks the S&P 500. It aims to deliver returns that roughly match the index -- which has an average annual growth rate of close to 10% over many decades.

The S&P 500 offers dividend income, too. As of this writing, it yielded around 1.4%. Dividend income is valuable for retirees and near-retirees (and many others) because it tends to arrive regularly, no matter what the economy is doing, and that income can be reinvested in more stock or withdrawn to help support you in retirement. Better still, dividends from healthy and growing companies tend to be increased over time. You can do better than the S&P 500's 1.4% dividend yield, though, if you park some money in one or more dividend-focused exchange-traded funds (ETFs).

Here are four well-regarded ETFs to consider.

1. Schwab U.S. Dividend Equity ETF

The Schwab U.S. Dividend Equity ETF (SCHD 0.44%) recently yielding a solid 3.6%, has a lot to recommend it, starting with an ultra-low expense ratio (annual fee) of just 0.06%. (That means that if you have $10,000 invested in it, you'll be paying about $6 per year.) It tracks the Dow Jones U.S. Dividend 100 index of 100 "high-dividend-yielding stocks in the U.S. with a record of consistently paying dividends, selected for fundamental strength relative to their peers, based on financial ratios."

This ETF's 10-year average annual return was recently 11.8%. The most heavily weighted stocks among its 100 holdings recently included Amgen, Cisco Systems, Broadcom, and AbbVie.

2. Vanguard Dividend Appreciation ETF

The Vanguard Dividend Appreciation ETF (VIG 0.23%) sports a recent dividend yield of 1.8% and an expense ratio of just 0.6%. It tracks the S&P U.S. Dividend Growers Index, which "is designed to measure the performance of U.S. companies that have followed a policy of consistently increasing dividends every year for at least 10 consecutive years. The index excludes the top 25% highest-yielding eligible companies from the index." Since many companies with ultra-high dividend yields are ones whose stocks have recently fallen, excluding the highest yielders can bolster returns.

This ETF's 10-year average annual return was recently 11.3%. The most heavily weighted stocks among its 300-plus holdings recently included Microsoft, Apple, UnitedHealth Group, and JPMorgan Chase.

3. Vanguard Real Estate ETF

Investors seeking income would do well to consider real estate investment trusts (REITs), which are companies that buy and lease out lots of properties, often focusing on particular niches such as apartments, industrial buildings, medical centers, retail outlets, storage facilities, and so on. By law they must pay out at least 90% of their income in dividends, so REITs often feature meaningful yields. The Vanguard Real Estate ETF (VNQ 0.39%) recently yielded 4.6% and charged a low expense ratio of 0.12%.

This ETF tracks the MSCI US Investable Market Real Estate 25/50 Index. Its 10-year average annual return was 6.5%. The most heavily weighted stocks among its 164 holdings recently included Prologis (specializing in logistics real estate such as warehouses), American Tower (specializing in telecommunication towers and data centers), Equinix (specializing in "digital infrastructure"), and Public Storage (specializing in storage facilities).

4. Vanguard International Dividend Appreciation ETF

Finally, dividend seekers might want to consider adding some international holdings to their portfolio. The Vanguard International Dividend Appreciation ETF (VIGI 0.21%) fits the bill, recently yielding 2.1% and charging an expense ratio of 0.15%. The ETF tracks the S&P Global Ex-US Dividend Growers Index, which "is designed to measure the performance of non-U.S. global companies that have followed a policy of consistently increasing dividends every year for at least 7 consecutive years. The index excludes the top 25% highest yielding eligible companies from the index."

This ETF's five-year average annual return was 5.2% -- which put it in the top quartile, among its peers. The most heavily weighted stocks among its 324 stock holdings recently included Novartis, Novo Nordisk, Nestle, and Toronto-Dominion Bank.

There are many other ETFs out there well worth considering. Whether you invest in ETFs or not, do be sure to consider dividend-paying stocks for your portfolio.