A few things that struck me:
Ep #431 - Barnabas asks: "Why do we never learn to leave the past alone?" Apparently that's one question he did indeed never learn.
Ep #693 - Whoever thought up Stokes' pencil anology to explain David's possession should be commended because it was excellent.
It never fails to astound me that whenever a fire was required in a scene on DS, a real fire was actually started in the studio (often on a duplicate set). I suppose there really was no other way to do it, but still, they were always taking an awful chance.
Ep #954 - Great scenes between Angelique and Nicholas. Her anger and his glee are the perfect counterbalance to each other. And, as always, Lara Parker and Humbert Allen Astredo played it all to perfection.