Well, I think that either my re-read of the Alchyemyst isn't far enough along - because I don't remember Gilgamesh as a character - or I am totally a idiot and my brain has done this:
(I L.O.V.E. that smilie by the way). But I see that here's another "vote" for my fav, Johnny Depp, to play a character. When he plays anything, it is an automatic ticket purchase by me, by the way (has been ever since I saw him for the first time on 21 Jump Street - and yes, I am giving away my age to some degree with that statement).
And, I love the choice of Hugh Laurie too. He is awesome. I think that Perenelle would be played excellently by Emma Thompson (let's face it she can play anything - comedy, drama, what ever - totally awesomely!) and the older Hekete - Helen Mirren. I am having a hard time deciding who would be cool as Scathy though.