Githzerai would be better than Githyanki, if its one or the other. I've played Githzerai in play by post and face to face gaming, as well as in Planescape: Torment and NWN2. Githyanki have only appeared in my games as bad guys.
D = Duergar (Psionic race)
G = Gnome
G = Genasi (Primal)
H = Half-orc (possibly also Primal)
S = Seraphim*
*I just made up that name, obviously, but I think they're going to have the Angelic descendent. I'm betting against Shadar-Kai until they develop the Shadow Power Source, which, as far as I know, isn't going to be in PHBII.