Association of periOperative Registered Nurses (Denver). AORN represents more than 160,000 perioperative nurses nationwide and includes more than 41,000 registered nurse members. The Denver Post named the organization to its "Top Workplaces" list in 2014 and a 2016 employee engagement survey found the average employee was "very satisfied" with his or her position. The organization offers an on-site fitness center, free yoga classes, healthy snacks and a recreation room with a massage chair, pool table and Xbox for employees to use. AORN also values professional development and provides tuition reimbursement for employees as well as on-site training workshops.