Giles graduated from DePauw University in 1955 and received his master's degree in 1956 from the Columbia University Graduate School of Journalism. He was a Nieman Fellow in 1966 and a Gannett professional-in-residence at the William Allen White School of Journalism at the University of Kansas. During his newspaper career, he served as managing editor of The Akron Beacon Journal, executive editor of The Rochester Democrat & Chronicle, and editor and publisher of The Detroit News.
Under Giles' editorship, The Akron Beacon Journal received the Pulitzer Prize in 1971 for coverage of the Kent State shootings, and The Detroit News won in 1994 for the newspaper's disclosures of a scandal in the Michigan House Fiscal Agency. He is the author of Newsroom Management: A Guide to Theory and Practice.
He worked at The Freedom Forum prior to taking the curatorship at Nieman in 2000. He retired as curator in 2011.
- Giles named Nieman Foundation curator Harvard University Gazette, August 21, 2000.