I second the better plasma fruit, and that vamps will autonomously drink plasma fruit in their inventory when low on thirst like they do packs.
And I think it'd be nice if better quality plasma fruit filled thirst more as well--then you'd have a real reason to evolve your plant. A perfect plasma fruit should give way more thirst than a normal one. It'd be really neat if they did something similar with packs made from fish and frogs--like, bigger and more expensive ones would make better packs.
I also second more plasma fruit foods that fill thirst--my foodie vampires are tired of fruit salads. We should be able to make plasma wedding cakes and birthday cakes with sufficient cooking and lore--my poor teen vamps need to blow out candles to age up, but can't really get anything from the cakes lol. Or the kid vamps who blow out the candles, and suddenly can't get filled up by their own birthday cake :-P
Vampire toddler clothes. And hair styles.
Being able to travel with vamps and invite them out and call them for more hours. I've never been able to find a time that works, but some people have managed between 8pm and 12 so I hear. It should be sunset to sunrise--so, any time between 8 and 4am, something like that.
Interaction for non-vampire sims to "offer to let feed." Let's say I have a vampire sim and a non vampire sim who are married: if the vampire "asks permission to drink," even if they have an excelent relationship, there's a chance the other sim will refuse. PLayers should have the option of initiating on the other end if they so choose. Heck, if they want, if the vampire has the guilty drinker weakness, there could be a chance THEY could might refuse (tho not a high one) unless they're very, very thirsty. And maybe voluntary feedings could have a chance of building relationship, rather than decreasing it--seems like a pretty intimate thing to do!
And, this is a long shot one I know lol--more vampire aspirations. I know we already have three, and there's plenty of other aspiration gaps that need filling, but since we're talking wiish lists for vampires: a vampire aspiration surrounding specifically using vampire powers, rather than juust building power points. Things like "mesmerize five sims" and "command a sim to ____". Stuff like that. And, a vampire aspiration for non-vampires. Either a vampire hunter or friend/lover of the vampires, or both. Something surrounding the building of vampire lore skill, but instead of being about becoming and being a vampire, it was about interacting with them and doing things like making garlic knots or curing vamps or even just chatting them up or whatever.