Healthcare for the employee is more valuable to the employer than is providing healthcare for the rest of the family members. Depending on the family situation, you're going to see significant differences in price between out of pocket costs for insurance of just the employee, vs cost for insuring the entire family. This is because in the first instance the insurance is more subsidized by the company (as a percentage of the total cost).
The costs to the company for insuring just the individual (mid-career) are in the neighborhood of $5000 per year. If this is all that's being negotiated (single person coverage) then I would use that amount as a baseline.
