I loved the original Dark Shadows and I loved the '91 revival even more, I think. Whatever you do with it, I think what's crucial is the characters. Each of them were extremely individual - Barnabas as the monster who was in love and tormented by his nature. Quentin, a ne'er-do-well with a secret. And so on.
My feeling is that it would be best as a show with an arc or series of arcs but it could definitely lose the constant re-telling of other classic horror/occult tales.
I'll always be fond of the original, though, practically filmed live with all of the falling sets, insects and stuck doors that entailed.