If you had to guess where a particular 78-year-old American retiree who plays bridge and has three great-grandchildren lives, what would you say?

Odds are you guessed Florida, or maybe Arizona -- two sunny states that have long been popular with the senior set.

But you'd be wrong, at least in this case. Lois O'Grady lives in Vermillion, South Dakota.

"It's an easy and comfortable place to live, and very safe and friendly," says O'Grady, who moved from the relatively bustling metropolis of Omaha to be closer to her family.

"It reminds me of Mayberry, if you are old enough to remember the old Andy Griffith TV show," O'Grady says.

There's not a whole lot going on in the area, O'Grady admits. The population is a shade over 10,000, and there aren't too many stores apart from a Wal-Mart.

But the region has another thing going for it: South Dakota was recently named the best state to retire in the nation, handily defeating retiree hot spots like Florida.

Indeed, by crunching an array of figures like cost of living, quality of healthcare, crime stats and tax burden, the financial information site Bankrate.com came up with a number of state winners you might not otherwise have guessed.

Other top selections included Colorado, Utah, North Dakota and Wyoming.

"The results were a complete surprise to me," says Chris Kahn, a research analyst at Bankrate.com. "For most retirees, these states are probably not part of the conversation."