Lifestyle Funds for the Inert

Here's the great thing about these funds: "Fidelity takes it upon itself to change the allocation, making it increasingly more conservative as the date approaches," Morningstar's Healy said. Because Fidelity rebalances the funds for you over the course of your investment lifetime, these offerings are probably best for the investor who wants to never pay attention to the markets and asset allocation again.

Fidelity tacks on a fractional additional expense for picking the funds for you, but 0.07% shouldn't be enough to keep you away.

2. Vanguard LifeStrategy Series

The Vanguard LifeStrategy series has plenty of selling points, too. First off, it categorizes the funds into four simple choices: Growth, Moderate Growth, Conservative Growth and Income. It's pretty straightforward -- the growth fund has 75%-80% of its assets in stocks; the income fund has about 80% in bonds and cash. Another highlight for these funds: the price. Because Vanguard primarily uses its low-cost index funds and doesn't add an additional fee, your expenses are extremely low.

The downside with Vanguard's LifeStrategy series: They don't allocate for you. Your portfolio remains static, unless you rebalance yourself. "Investors need to check at the end of every year to determine if their asset-allocation needs have changed," said Ibbotson's Majeski.

3. T. Rowe Price Retirement Series

Like the Fidelity series, T. Rowe Price's offerings are labeled by a year: 2010 up through 2040 -- and they rebalance for you over the course of your investment lifetime. The T. Rowe Price Retirement Income fund is similar to Fidelity's Freedom Income offering, except it's a little less conservative -- a nearly 40% stock weighting, compared to Fidelity Freedom's 17%.

Like the Vanguard series, the T. Rowe series doesn't levy any additional fees -- only an averaged-out fee of all the funds the lifestyle fund holds.

Like Fidelity and Vanguard, T. Rowe's series makes for a good bet because the firm behind it has the heft to offer quality offerings across all asset classes. T. Rowe Price is a stellar shop, so the inert investor is in good hands.

Other fund firms offer variations of lifestyle funds. If investors are lucky enough to have employee-retirement plans that offer a luxury of choices, they need to make sure that they go with a firm like the three above that have the ability to offer a wide range of stellar funds.

Lifestyle funds aren't for everyone, but they're much better than nothing -- and they give you more time to do what you really love.