Wealth and health are both important in retirement, of course, although the latter in particular can decline as people age.

And while those in the highest asset quartile are usually those most satisfied in retirement, that's getting harder to come by as pensions disappear in favor of defined contribution plans.

In 1998, while overall 60.5 percent of retirees said they were very satisfied with retirement, among those in the highest asset quartile, the percentage was 72.5.

And in 2012, overall 48.6 percent said they were very satisfied, but in the highest asset quartile the percentage was 62.5. According to the report, the net worth of those in the highest asset quartile averaged $374,398 in 1998, compared with $202,918 for all participants.

To see the waning influence of pensions on wealth and happiness, consider this: study respondents who retired with pension benefits were more likely to be "very satisfied" after 15 years in retirement, while those without them were not—57.5 percent, compared with 46.5 percent, respectively.

Health—or its lack—has a huge effect on happiness during retirement. Just under 80 percent of healthy respondents were among the "very satisfied" group, while among those in poor health, only 25.6 percent said they were "very satisfied."

And, no matter their income group, retirees experienced similar trends of satisfaction and dissatisfaction.

The most prosperous, and "very satisfied," among respondents reported an 8.9 percent decrease from that top level of satisfaction from 1998 to 2012, while those in the lowest income bracket reported a 12.2 percent decrease.