Childrens Hospital Los Angeles. No apostrophe. Unreal. Would you trust these peopleses with your singular child?
(Update: I wrote to the hospital through its Web site, and a PR person was nice enough to answer. Apparently this question comes up a lot. It seems the error is an old one, and attempts to insert the apostrophe have been rebuffed by staff lawyers in the name of consistency with the articles of incorporation. Still reprehensible, but to my mind not as bad as the newfangled-branding-strategy explanation I had expected.)