I've heard about Passions being similar to Dark Shadows but I've seen Port Charles and that is the show that  reminds me of Dark Shadows. It has the same New England feel and it had vampires and now they have angels.  Port Charles does their stories in 13 week-arcs also.

The main difference I see is that Port Charles' vampire was youthful. Jonathan Frid on DS wasn't in the bloom of youth but he was a hit on DS. Soap operas today emphasize youth to the extreme. Joan Bennett and Jonathan Frid probably wouldn't get roles today in a Dark Shadows-type of soap.  

I think Joan Bennett was fabulous btw. I loved her as Naomi Collins and I like her as Elizabeth Collins Stoddard.