With this it mostly depends on the sim, the very first that I ever made though was actually because Straud was lurking around my Wren household trying to get into the house after I initially bought the pack >.>
I did what any perfectly rational person would do about the situation... I made Darth Maul, (i mean sith eyes are literally right there in the creation screen, I had to.) raised him to grand master vampire with third tier strength and other such powers and took him around stripping the powers from every other vampire in that particular game, then had him depower and ghostify Straud... and.. he works surprisingly perfectly as a vampire.. dark meditation looks amazing on him.
I have created other vampires since then, and usually base their powers around the personality of the sim and what they wanted to accomplish when they became vampires to begin with.
My general setup is that I have a number of "turned" vampires built around two "pure" vampires, my heroic character Veralesca Drakul, and my full on evil vampire Vladmir Drakul (who stole her name, their entire storyline is that they have been feuding for centuries, he's obsessed with her.)
I worked on getting the two of them most every power in the book, with their weaknesses reflecting the fact that Veralesca is closer to human with a lot of trauma in her history (nightmares, and restlessness for example) while Vladmir is a flat out monster with full on weakness against sunlight instead of being a day walker like Veralesca, insatiable thirst and the sloppy drinker trait.
Though all of my vampires have the withered stomach weakness which I based entirely around Underworld, it wouldn't make sense to me for them to keep eating normal food.
With the "turned" characters like Hans (Frozen-world) I gave him the more manipulation-based powers, because he was already like that beforehand, his entire goal was to have control over people-- so that's what he gained from Vladmir turning him
Anna on the other hand is getting strength based powers because her entire goal when Veralesca turned her was to protect Elsa who was soul drained protecting her from Vladmir, and to take Arendelle back from him and Hans.
I also recreated the Cullen family (based on their visual novel appearance) as more traditional vampires (they all have fangs! :open_mouth: ) with the alteration that in their backstory it was Veralesca who turned Carlisle after finding him soul drained (again by Vladmir)
Their powers and weaknesses are still in line with what they already had for the most part, they all have the guilty drinker trait, and they are all full on day walkers.