Mine is a character that has:
Illusion of course, mind games.
Conjuration (but only for summoning the undead).

So, what now? What would you add? Destruction? Fire? Ice?
Would you add Alteration for the sake of Paralyze? Uuhhmm..

It depends, generally vampire =/= sorceror so destruction would be off the menu for a typical vampire. Their abilities would centre more around illusion and alteration imo.

That being said, I'm yet to bump into a vampire in-game who wasn't a mage.. I miss the various vampire warriors you'd find in Oblivion.

I once saw a warrior, orc that was a vampire.. in a place.. with other vampires that was spell casters I think, so they do excist!

Anyhow, I can't see myself getting far without Destruction as a vampire with only Illusion and Alteration, hmm!
I really want to join the Dark Brotherhood and be a vampire that use Stealth or Invisibility, murdering with spells? I am not sure.
Don't like the dagger stuff because it's random when you get to do those cool killings. Spells is a bit cooler then, but is it possible to get a murder with spell rather then a assault? When I do not have the sneak multiplier?