Where are the After Effects workspaces saved?
According to Adobe:

Workspaces are stored in XML files in the preferences folder. With some caveats regarding monitor size and layout, these workspaces can be moved to another computer and used there.

Windows:

[drive]:\Users\[user_name]\AppData\Roaming\Adobe\After Effects\[version]\ModifiedWorkspaces

Mac OS: 

[drive]/Users/[user_name]/Library/Preferences/Adobe/After Effects/[version]/ModifiedWorkspaces