Another clue is the pricing tiers available. Generally, the more choices, the more cost savings the employer is giving to employees.

Some companies offer a family rate, but they may charge less to add just your kids without a spouse. "They're giving a break to people to cover your spouse elsewhere," says Tracy Watts, a senior partner at Mercer, a benefits consultant.

At generous companies, there is also typically also no surcharge or exclusion for working spouses who could get their own plans, which is becoming more prevalent nationwide, says Kesmodel.

What's My Deductible?

A low deductible is not the only marker of a good plan, says Jennifer Benz, who runs her own benefits firm based in San Francisco. The average healthcare deductible nationally for a single employee is $1,318, according to Kaiser, which has been pushed to that level because about 24 percent of employees are now in high-deductible health plans, which have deductibles over $1,500 per year.

In the best high-deductible plans, Benz says the company will contribute enough into a Health Savings Account to make the out-of-pocket costs for the employee equivalent to having a $250 individual deductible.

But then the money in that HSA is portable if the employee changes jobs and can be saved for retirement, tax-free. For young, healthy workers, this can build to a considerable nest egg in just a few years.

"People think they are less valuable, but they might be more valuable," Benz says.

What's Covered?

Coverage of infertility treatments is a common perk in Silicon Valley, says Benz. Some larger firms, which foot the cost of the healthcare bills themselves, go beyond the typical $3,000 to $5,000 to offer $15,000 worth of coverage, which is enough to cover a round of in-vitro fertilization.