Charles Champlin, the former Los Angeles Times arts editor, film critic and columnist whose insightful, elegantly written reviews and columns informed and entertained readers for decades, died Sunday at his Los Angeles home. He was 88. The cause was complications of Alzheimer's disease, said his son, Charles Champlin Jr. The Harvard-educated Champlin had worked 17 years at Life and Time magazines before joining The Times as entertainment editor and three-times-a-week columnist in 1965.