Perhaps Ken Levine?
He gets interviewed by quite a few sites when it's time to press his games, but it would be cool to hear what Steve would have to ask him. I'd second the recommendation for Tim Schaefer, hearing that guy talk is quite entertaining. Also I'd toss out the name Ragnar Tørnquist (ooh asciiz) cause Dreamfall had some pretty unique decisions made, and finally the Portal devs, I don't even know their names, but hey, for the love of Jesus, they should be interviewed.
