For some American workers, picking the right health insurance is becoming more like hunting for the perfect business suit: It takes some shopping around to find a good fit and avoid sticker shock.

In a major shift in employer-sponsored health insurance coverage, companies such as Sears Holdings Corp. and Darden Restaurants Inc. are giving employees a fixed amount of money and allowing them to choose their own coverage based on their individual needs.

The approach, called defined contribution health insurance, contrasts to the decades-old practice by most U.S. employers of offering workers a one-size-fits-all plan. It also means American workers who've grown accustomed to having their benefits chosen for them could wind up with bigger bills and inadequate coverage if they don't choose wisely.