In my D&D group we all made characters of our fantasy selves. They would be primarily used on days where not enough players showed up to run a normal campaign, so we could switch to the light-hearted, 4th-wall breaking, mostly improvised "Us" campaign. Right now we're exploring the ghostly apparition of our city's old demolished shopping mall that has reappeared.
Anyway, a good friend of mine in the group wants to make a character, and he wants it to be primarily an Ur-Priest. He is still debating, however, what do do with his class levels before and after the Ur-Priest levels. He isn't looking for anything earth-shattering in power, but would like something cohesive for the build. He isn't married to taking all 10 levels in the PrC, but he certainly wants ten levels of it's casting and really likes the flavor of the Steal Spell-Like Ability ability. My first suggestion was some sort of arcane caster so the Ur-Priest caster level would stay up (and for the skills needed), and then go into Mystic Theurge and finish off any remaining levels with more Beguiler. So far he's a level 3 Beguiler. None of this is set in stone.
My question is what kind of set-ups would make for a fun Ur-Priest? I was thinking about classes that need Wisdom as a stat and could mesh okay, but all I came up with was Psychic Warrior. I also thought it would be cool to squeeze in Chameleon levels just for shits and floating feat fun (item creation feats came to mind). I know the question seems really broad, but I'm not looking for exact build suggestions; just general guidelines. So in conclusion, what classes and PrCs do you find that mesh well with the Ur-Priest?