I think the things that can make them boring compared to other sims, at least for me, is that they have more active hours per day and they are always the same while my other families are always aging and moving through the generations.
I use the hibernate option on the coffins for the first problem. Sometimes I have to do it twice because they'll get up on their own the first time, but it's supposed to keep them in the coffin until you wake them up. I keep my vampires with sun weakness in their coffins all day long, and the others in theirs during the parts of the day when other household members are at school/work so part of the day goes on superspeed.
For the other, there are a few options. One is to change things up with a story element now and then. I just had one vampire sim use the vampire cure to "slay" the head vampire of Straud Manor and turn her mortal again. I had her do the same thing to Vlad a while back and feed him to his cowplant. Now I have a new household with the former vampire turned spellcaster now in an attempt to learn the spell to resurrect her dead lover, and their teenage vampire daughter adjusting to life without other vampires. And the Straud Manor household will now have new blood and new stories.
In my multi-generational vampire family, I'm about to move the heir out into her own house and leave her parents behind, rather than have all generations live together like I do in most of my multi-gen households. It's getting too crowded since no one dies. The parents will no longer be part of my regular rotation, but I might pop into their household as part of a story or to pursue a goal (they are the couple who are trying to woohoo in every available spot so I'll have to have them catch up with my newer packs at some point). This way they don't get stale the way rotating to the same house made up of exactly the same sims in exactly the same life stage every time could be.
As far as making them feel more like vampires, that does require work on the part of the player to decide how and when to use their powers and how to have them feed. Good vampires are harder to keep interesting than mean, mischievous or evil ones because so many of the available powers are about messing with other sims. I usually have the good ones focus on romance, often with non-vampires, and raising a family.