How about these 3 categories:
Global (the whole world)
Child Boards: Classic, Revised, AA50, Spring 1942, 1942 SE, 1941, Global 1940
Theater (Pacific, and/or Europe)
Child Boards: Classic Europe, Classic Pacific, Pacific 1940, Europe 1940
Local (Guadalcanal, D-Day, etc)
Child Boards: D-Day, Battle of the Bulge, Guadalcanal
Or alternatives:
Have sections for all the main & popular new games:
1941
1942 SE
Global 1940 SE
Europe 1940 SE
Pacific 1940 SE
AA 50th
Then have a section for all the old games, with each as a child:
Classic, Revised, Guadalcanal, etc