Ebert did a commentary track on the DVD of Dark City that could be used to teach film school. Absolutely illuminating.
(Edit: grave, not graveyard. Added link to his review of the film.)
[0] https://www.rogerebert.com/reviews/great-movie-grave-of-the-...
As a rule, I avoid depressing content and was wholly unprepared for the emotional pounding I got.
Watch (both) if you haven't, they're great movies, but brace yourself.