I don't get nearly enough vampire activity in my main game. But I do have a very populated world, so maybe they just aren't spawning that much. I had a sim out in the city for a festival, and when it was over late into the night, and my sim's friends were gone and she wanted to go home, I got that notification that said she couldn't leave while a vampire was breaking in. So I got excited and started looking around for it, and suddenly a black streak whooshed by and disappeared into the city. I didn't even get a good look at it, but it was still a little exciting. :)
I have found, though, if you want to prevent them from breaking into your home lots and feeding on your sims, locking your doors at night definitely helps. There is a power that some vampires have that allows them to come in anyway, but not all of them have it, so it really makes a difference.
Vampires are amazing. <3
