Thank-you for the very thorough write-up!

I think I'll ditch the stock case & use one which also covers (or better protects) the screen.
It must be easy to remove the screen cover or it should not impede interaction with the screen.
It must also be very slim-line with the body of the phone, like the stock case.
It should be well cut so that things that need exposure aren't impeded & are easily accessible.
Ideally (but not imperative) it should also enable me to attach a belt-clip.

In my lengthy quest to find the perfect case (for me) for my N900, I recall settling on a otterbox.
I don't see anything for the N9 from them yet, I do hope they release something soon.

I do like the idea of a protector, so I'll probably also get the skinomi or another make/model.
Not sure about full-body though, seems kinda redundant once one has a decent case.