I've been toying with the idea of including vampires in my saga at some point down the road. I was a big fan of the theme behind Vampire: the Masquerade, although I never had the chance to play it, and I'd like to pay it homage by cribbing a bit of its style about what it means to be a vampire.
It's all still rudimentary right now, because I have several hooks and arcs I'm working on setting up so my players can knock them back down. While I let my ideas mature, I was hoping to find some inspiration in how other people had used vampires in their games, if you wouldn't mind obliging me.
You would find Ars Magica 3rd edition very interesting. In that version, the history of House Tremere and Clan Tremere were merged, so that the former turned into the latter. In that era, White Wolf owned the game and was folding Ars Magica into the World of Darkness.
But third edition is not much liked by the Ars community for precisely that reason; many feel that Ars Magica is best when it is Ars Magica, not the World of Darkness. And vampire legends in the Middle Ages are very different than they are in the 20th century, so much so that for many players medieval vampires are not very recognizable.
In 4th edition vampires were taken back out of House Tremere, and the move was completed by 5th edition.
There is a lot on vampires in Ars in the Transylvanian Tribunal book. The authors of that book worked hard to create a setting in which you could do gothic horror and Ars Magica. Also, vampires appear in Realms of Power: Faerie. So I recommend taking a look at those books for some well researched and useful ideas.
I think it depends on what kind of vampires you're thinking of using. Against the Dark (as well as the Tremere section of HoH:TL) has information on Ars Magica-style vampires, which tend to be faries that kill you in your sleep or try to suck the breath out of you. Or alternately, you get the sort of Nosferatu-style "rotting corpses that are wandering around and trying to kill you" kind of undead. (EDIT - ninja'd by DoctorComics.)
I THINK there are demonic vampires as well, but I don't specifically recall them. (As, after all - what good does drinking someone's blood do in order to tempt humanity into sin and rejecting the Divine?)
That being said, I can certainly appreciate the White Wolf's take on the Vampire mythos - each clan more-or-less represented a style or theme of vampire. (Tremere = dark sorcerer, Ventrue = decadent European nobility, Brujah = Lost Boys Rebels, etc.) However, most of those themes are relatively modern literary or movie creations, and as such don't necessarily fit into the Ars Magic metaphysic.
So - to answer your question: No. I have not used vampires in Ars Magica, mainly because I haven't run an Eastern European or Tremere-centric game (which is where vampires naturally show up in AM, usually.)
that being said - if you're looking for the "The beast I am, lest the best I become" kind of roleplaying, you could go for the half-infernal children, as described in RoP:I. These are mortals with a demonic parent, and (at least superficially) fit the angst-ridden vampires of WW. The main difference being, of course, is that their demonic parent has an active interest in corrupting them, and there's no "I must use my evil power, or else I will become even more evil" inherent in their narrative. (Although their demonic parent would like them to THINK that.)
EDIT - so in THAT sense, you could probably set up a campaign that uses a demon (or a group of demons) setting up an extended family, and trying to get them to corrupt society as a whole. They won't be vampires, but I would imagine you'd have a similar feel to the organization. (Although you'd have to explain how a bunch of demons managed to work together for any real extended period of time. It may simply be that a couple of demons had the same idea, and refuse to acknowledge that other demons are doing it, and the Camarilla-expy is the logical consequence of their mortal children going "What the actual Hell? Screw that, I'm doing my own thing."
We had an excellent storyline where a powerful Seeker at Durenmar sent the characters deep into Egypt to follow up on some leads regarding ancient magic. This lead us deep into the deserts, getting lost, and finally encountering the den of a vampire and his brood. (The vampire was lifted from the World of Darkness, and was of the Follower of Set clan.) The vampire was aware of the Order, and had several agents in Europe. The agents had planted the rumors about this ancient egyptian magic in the right places, and the Seeker had picked up on it, sending our characters to their doom. We barely made it out alive, and that Vampire is still down there somewhere, working his nefarious immortal schemes to amass wealth and power....
Our assumption is that the Vampire was planning on capturing us and learning more about Hermetic magic, but we didn't stick around long enough to find out.
One example is the vrykolakas from The Sundered Eagle.
In any case, we've only ever used vampires as monstrous antagonists. I did have a dhampir vampire hunter character towards the end of our last saga, though. She was loads of fun to play.
Well vampires may be good and strong enemies for your magi.
One vampire beginner was one of the first encounters my players had - and they saved a poor young sheperdess from him. The magi know the vampire is still "alive" (or not definitely dead though) and growing in a near city. They don't bother about it - but his revenge will come sooner or later.
I know there is a Tribunal book about that stuff (Transylvanian Tribunal of course) but I don't have it.
Oh, I totally forgot I had Hugh of Flambeau captured by Novgorod vampires, and the PCs had to go in and rescue him. Turned out totally anticlimactic, because when the boss vampire showed up, the first attack on him exploded.
I get that's a trademark Ars Magica move. But sometimes it tells a worse story, not a better one.
They would fit pretty well as faeries. 5th edition faes are among the most scary and creepy creatures I have seen in any game. Think a moment about them: they are some kind of things built on narratives and stories that feeds on vitality. While most faeries feed from that vitality in subtle and indirect ways (making the characters play their games, making people being scared or follow odd rites), some can go to the straigh route (after all there is also vitality in people's blood, flesh and bones). And if one dies, then another can occupy their role, seeming that the faerie didn't actually die (if they really can do so). And these who are cognizant can even change themselves to get vitality in other ways.
That makes quite a direct way of making vampires as some kind of blood-drinking faeries (...or flesh eaters, or bone suckers, or eyeballs collectors...) that you can play as a classic vampire story, but it also opens a huge gate of dreadful possibilities, from the twisted wicked ways of a nasty dark faerie court with a higly cognizant mighty ruler to the giant monstruous butterflies that suck the minds of anyone who sees their wings them a la China Miéville's Perdido Street Station.
Also faes sometimes organize themselves in complicated ways, which would let you use vampires and put your players in a kind of game they think they understand, a classical vampire story, only to discover that these faes were only part of the bottom hierarchy behind some pretty dark, sinister and ancient fae court.
Before Realms of Power: Faerie was released, I designed one as a sort of Infernal Ghost for Halloween game. It worked tolerably well, but, with the current status of the realms, Faerie definitely makes more sense - most of the time, at least.