Courses covering the following genres would be great:
Westerns, Musicals, Detectives/Mysteries, Theatrical Cartoons & Short Subjects, Gangsters/Prison.
Other possibilities: Focus on directors such as Hitchcock, Ford, Capra and Hawks.
Focus on decades such as 1930's or 1930's & 1940's.
Focus on studios, either individually or in comparison.
Focus on eras such as silent, pre-code or pre-WW2/post-WW2