Here’s what to expect when your employer gives you choices during open-enrollment season this fall.Employers will be making some changes to their health-insurance plans for 2011 because of health-care reform — such as offering coverage to children up to age 26 — and as a way to help control rising health-care costs. A recent survey of large companies by the National Business Group on Health found that employers estimate their health-care-benefit costs will increase by an average of 8.9% in 2011, compared with an average increase of 7% this year. These employers are continuing to boost premiums and co-payments, but they’re also beefing up programs that encourage employees to lower their medical expenses.