Thanks for the responses! My players are pretty set on Orlanthi culture, and a couple even have favorite cults they'd like to play picked out. I do want to run a Lunar campaign with them eventually though.
Right now my thought is to involve the players, whether directly or indirectly, in some sort of struggle between the various aspects of Ralzakark. Maybe the scorpion-arm aspect thinks the unicorn-head aspect is becoming too impure (i.e. orderly) and orchestrates a coup, maybe one aspect wants to seize whatever's in the Cleft of Dorasta while the other thinks it's a bad idea, maybe the human-like aspect wants to manipulate the PCs into turning the other aspects against each other... lots of options.
My question now is - if it came down to it, would a follower of a storm tribe cult (assuming no Uroxi) support the 'orderly chaos' of the unicorn-head aspect over the 'chaotic chaos' of the scorpion-arm aspect? Assuming they were forced to choose one or die, would the 'typical' storm tribe cultist prefer death or would they be open to adopting a 'lesser of two evils' rationale? What sorts of situations would force their hand when it comes to supporting something as evil as Ralzakark?