I am using what I call "parent tagging". Here is an example of structure :
I would like EverNote to add automatically the parent tag(s) when I add a children tag to a note. Of course, all the tags would not be concerned (I could select the concerned tag in an option menu).
I find a great restaurant in Paris, on internet. I add its info to a note and I tag it with "Paris. Then, EverNote would add automatically the tags "France" and "Trips" to my note.
The example here, and the structure are simple. But when you have an architecture with 5+ layers, it's time saving ; and you are sure not to forget any tags. Then, it allows me to see what nice notes I have for my next trip in France, for example (by filtering with the "France" tag).
I know there are some automation tools, not developed by EverNote that exist on internet ; but I would like to have it as a native feature.