I don't think you really need to toggle vampires off because they're not that intrusive.
I started a brand new game last night with Steve Vogel, one of the promo-Sims. I used the aspiration and traits listed for him on Wiki. He moved into Sandtrap Flat where he met Johnny Zest right away. They clicked because they both want to be entertainers. Shortly after Johnny arrived, Caleb Vatore knocked on the door. Steve and Caleb clicked because they both have the Foodie trait. At the same time I noticed that Steve had also become acquaintances with several Sims that were simply walking or jogging past his lot. Sims that he didn't actually talk to - Katrina Caliente, Geoffrey Landgraab, Mortimer Goth and Don Lothario. Now that, to me, is intrusive.
Steve went to work on day 2 as an Entertainer. After work he went to the Onion Juice Bar where he met several more Sims - no vampires. Caleb zipped in around 10pm and zipped out around midnight.
On day 3 Steve came home from work, watched TV for a bit and read a book. I have him working on aspiration goals as well as work-related tasks. He was busy writing jokes at 11:30pm when Lilith Vatore came to visit. Steve and Lilith were chatting and watching TV when Vlad arrived around midnight. The three chatted for a bit then Vlad went to play Sims Forever on Steve's new computer while Steve and Lilith continued to chat while watching TV. Nothing out of the ordinary except that Lilith and Vlad came to visit at at night instead of during the day. I could have easily opted for Steve not to answer the door but I didn't.
So, now he knows all three of the pre-made vampires and he has two new friends - Johnny Zest and Caleb Vatore. One of the vampires might surprise me later and pull a vampire "I want to bite your neck" thing but it's my understanding that the Sim can choose not to be turned. That would probably be my choice for Steve.
It's a very new game. I like Steve. He has an aspiration that I've never tried and traits that I usually avoid so we'll see how it goes. I mostly needed it to harvest pre-made households to clean up for my main game.
So far, I really don't think that vampires are as bad as some people have made them out to be. It seems to boil down to choices made by the player. Believe me, I made some pretty bad ones in another of my saved games.