The music geek in me is forcing me to remark that no one here has pointed out one of the more important innovations of the original "Dark Shadows" series.
Although I was not a fan (it came on while I was still in school

), I was able to catch a few episodes when I found myself at home during the day.
Most "soap operas" up to this time had little in the way of musical accompaniment, and what little there was usually consisted of a few chords supplied by an electronic organ (a fact that Carol Burnett delighted in making fun of in her hilarious "As The Stomach Turns" parodies

). "Dark Shadows" was the very first "soaper" to have
a musical score provided by a FULL ORCHESTRA. This important addition was much remarked upon at the time and contributed enormously to the "classy" atmosphere of the show.
Little bit o' trivia--I wonder how many people here know why these serialized stories were/are called "soap operas". I used to think that it had to do with the fact that they were descendants of the old Victorian melodramas, wherein such things as snowstorms were simulated on stage by falling soap flakes. In fact, it comes from the fact that most of the early radio serials (such as "The Loves of Helen Trent") were sponsored by companies such as Procter and Gamble

.