In the Contents pane it would be really nice to be able to either sort the layers by visibility or if there was a "List by Visibility" tab on the pane. This way when I have a project with a WHOLE bunch of layers and I get the project to the final stage, then I could select all the layers that are turned off and remove them from the project or Group them so I can minimize that list of layers.
It would really help with cleaning up projects to be able to select all the layers that aren't currently visible and either remove them or "Group" them so I could clean up the contents pane.