CHICAGO, Nov. 15 - Gov. Rod R. Blagojevich signed a measure on Tuesday intended to allow all children in Illinois, including those in working-class and middle-class families, to obtain health insurance. National experts on health care said the new law, which will offer discounts on premiums for those who qualify, was the broadest plan to insure children by any state. Political leaders in other states, the experts said, are certain to be watching whether Illinois succeeds in expanding coverage to its 250,000 children who are now uninsured, about half of whom are not from the poorest families but from families...