Upvoted and throwing my 2 cents in.
I use Evernote a lot for school. I don't need a crazy amount of nesting, but one more layer (making a total of three layers) would be nice. I would like to set up my School stack so that I could have a School stack with a notebook for a current class at the top level, then when the semester is done, I could move the whole notebook into an archive. I can do this with 3 layers:
School
Class 201
Class 202
School Archive
Class 101
Class 102
Instead, this is my current setup:
School
Current Semester (tag:class 201, tag:class 202)
School Archive (tag:class 101, tag:class 102)
It does the job, but isn't as clean, especially if I need to go back and reference notes in previous classes.