Batch or Group Replace Layers
It would be awesome if AE could replace multiple layers in the timeline with multiple items in the Project Panel (while holding the Option key) like some sort of group replace mechanism. The order in which the files in the Project panel could match the existing selected layers in the timeline could be based on which item in the Project Panel was clicked first, second, third, etc.
Or even better: right-click on the selected items in the Project panel and make a new 'group replace' menu? Maybe a pop window appears that confirms the layers to be replaced with the items from the Project Panel.