I always loose interest in playing vampires after a while. Even when playing them full out evil... it gets dull.
I tend to play spellcasters as "Sims who can cast spells" rather than "Spellcaster Sims" so I always feel like there's more I can do, because being a spellcaster doesn't have to be their primary focus in life. I've played several spellcasters who don't get any further than Scruberroo or Repario and never make it to the Acolyte stage, because they're more interested in being a writer, or an Astronaut or whatever.
Vampires you always have to be aware of their vampire-ness. Spellcasters can take some time away from being spellcasters.