Could there possibly be a [canonical-answer] moderator-only(or otherwise officiated) tag on the main site to single out good canonical questions? Currently, a list of canonical questions is hidden somewhere in meta where panicky users that have just panicked with unmet dependencies, to cite an example. Possible options listed below. If this is approved, then there should be a prominent location with these questions or at least a prompt to look through them before posting your own question.
I would argue that this isn't needed. Why? Because if it really is a a canonical question, and it is a well done, popular question, it shows up as the first question in Google, or in here
I don't think this is needed, and that we should spend our time making canonical questions awesomer (that is a word, right?) instead of trying to make our really simple mission - questions and answers even more complicated.
Let's not avoid clutter with common duplicates because we don't prompt people to look at canonical questions because we don't even have an official list readily available at a prominent location within the main site.
It should be moderator-only.
It should be something you can propose with enough reputation, and approved by somebody with even more reputation.
It should be something you can vote on that isn't just approved, but requires a certain amount of "canonical" votes.