Yeah, there are lots of fun Themes to choose from.
I am debating between Wizard's Apprentice (Freggo talks about his Wizard mentor often enough) and Chevalier, which seems to be the theme closest to a character trying to be a hero. I don't really like the horse-riding part of Chevalier though, and the Apprentice crunch appeals slightly more, so I think I'm going with that.
For Ah-Shahran, the Seer Theme seems to be the most natural match, but the Cast Fortune power might be tricky in PBP. It seems like the sort of power that would result in enthusiastic geeky planning by the power-gamers at the table. On the other hand, maybe it would be a good think to encourage us to plan a bit together. The Noble theme doesn't seem to match the manic, slightly insane but compassionate warrior with ghost-animal friends thing. Though I suppose it could just be another personality that comes out from time to time. The Alchemist theme would represent another facet to add to the already multi-faceted Ah-Shahran, but it certainly would suit him.