If you're familiar with the Spirit Shaman from Complete Divine, Pale, then that could be one option for a Charisma-based semi-prepared caster. You'd get access to the Druid spell list, and would get to choose which spells you had access to each day, but would then get to spontaneously cast those spells. The class uses Charisma for save DCs, and while it uses Wisdom for spells per day, a Dragonlance feat called Dynamic Priest could fix that little problem easily, assuming Zaer would allow it.
As for the Sha'ir Sain mentioned, that one is in Dragon Magazine Compendium. It's similar to the Spirit Shaman in how it functions, but gains spells from the Sorcerer/Wizard list and is fully Charisma-based from the start. It's got more of an Arabian flavor to it, but coming from a desert setting could be an interesting choice for a vampire. You could have been the follower of some other deity (a river goddess, perhaps?), and have been raped on the altar of one of her temples by the harsh, merciless sun god of your world. Then, as punishment for this, your patron deity cursed you to be unable to bear the light of the sun, casting you out but at the same time ensuring that the sun god would never again be able to have you.
Edit: And if you'd like to play a small race, Dragon Magazine 350 has the D'hin'ni, a plane touched Halfling race that has a little Djinni blood in its veins. It's got a Charisma bonus and prestidigitation at-will, so it could be pretty fun and flavorful to try. ^^