I get several vampires knocking on my Sims doors every night. Most of them though, that's as far as it goes, they never try to actually break-in. Oh and they're ALL elder townies, except for Caleb, Lilith and Vlad. Those three do try to break in. It's funny watching them go through the motions over and over again when they can't get in. I always lock bedroom doors to just household members and sometimes any doors leading outside.
Sometimes I'll leave the front door unlocked though. Vampires can be beneficial. After they give up trying to bite your Sims, they'll hang around for a bit, take out your trash, mop floors, etc., before they leave. lol Just make sure you lock any doors in rooms adjacent to locked bedrooms. They might not be able to actually bite your Sims, but they can and WILL still mesmerize them through a wall. I've had that happen a couple times. o.O
