SimplySara, Opinions vary widely and the phobia in the markets about interest rates is causing wide opinion swings among pros and amateurs alike. So here's a (admittedly long) opinion FWIW from someone with a reasonably high net worth that's also growing more income producing troops...
First, if you have enough investments to retire, then you may have already read bogleheads.org and the forum for 3 or 4 fund "lazy portfolios". Withdrawing as such a portfolio grows over time is "income". That would include stocks and bond ETFs with low expenses in %ages depending on your age and years to retirement. This is my "foundation" investment FWIW.
Then there's the desire for a real income generating fund that's tax advantaged (or mostly advantaged) to minimize capital gains. As others mentioned, chasing yields is deadly, but making calculated bets on consistent performers is good. FWIW, I have several years of positive results (w/solid payouts during the tough stretch of 2008-11) with REIT, Muni and MLPs in the Energy (Oil/Gas) sector for pipelines/infrastructure... Get the details from the websites for JRS, MHI, NKV and JMF closed end funds (the last one is in MLPs but avoids some of the tax headaches and risk of owning just 1 or 2 MLPs that might get whacked by an individual company's failings in some way). These go up and down in value but payout is in the 5-8% range consistently tax exempt or advantaged and they retain investment value well on average (not always, just average). This is my "anything over $20K early IRA conversion withdrawal and I need fun money" investment. As I see entry points in these, I'm heading to about a 50/50 split of my "foundation" and these assets within which, there's a 70/30 split of REIT/Muni to MLPs (now's a good time to build an MLP position based on valuations!).
From this point, the opinions really get interesting... FWIW, here's another one... We just completed the "post great recession" deficit spending and our government's financial health credit rating isn't what it once was (I simplify the situation a bit here, but you get the idea). We just had the 4th highest deficits as a % of GDP in our history (
http://www.usgovernmentspending.com/federal_deficit_chart.html) At some point, we will have a smaller crisis that by itself wouldn't hurt much, but due to recent history, we won't be able to borrow or print money to get out of trouble as other countries will demand a premium to lend to us (among other problems). That's the argument for treating this somewhat like the early 70s where we changed the structure of our financial system (ie, Nixon dismantling Breton Woods gold conversion) plus other "everyone gets what they want from the government" irrational forces at the time let the inflation genie out of the bottle through the early 80s. When this happens, the Closed End funds above will become "unpopular" and lose real value unlike the "Great Recession" period unless you get one that "floats" with the rates or you catch the "downslope" of the inflation curve with a long term position that pays off for that period. In this case, frankly nothing works very well... Equities are not as bullish when real purchasing power is declining and a lot of bond and dividend paying funds are challenged when inflation rises... this is when things like real estate and strangely TIPS government securities, short term Munis and maybe metals are where you ride it out until the system purges the financial demons. I was too young at the time to know why I had family buying gold and Treasury bills back in the day or why my parents thought our house was going to be their retirement plan as it skyrocketed in value. Now I know, these were just the only things that were generally keeping up with the decrease in real purchasing power that is inflation exceeding wage growth. Fewer people got rich during that window, but those who kept steadily investing really did well when inflation dropped and the 90s bull markets ran wild. Ahhh, the good (and bad) 'ol days... Opinions aside, I hope this helped some... good luck!
Bottom line IMO is there's no "safe" single income stream. Build at least 2 of 3 above and be ready to shift towards the 3rd based on the situation using history as a compass... Unfortunately, there's no financial GPS though!