Well, I've never played FFXI so I'm not familiar with its technical aspects, but I have a few suggestions:
- I like that there are a lot of classes to choose from, but it seems like some of them are repetitive or could be merged into one class (ex. soldier & fighter, hunter & beastmaster)
- in World of Warcraft, there's an area called Duskwood, which is really dark and spooky, and has an interesting backstory involving zombies (I think). I think something vaguely like that would be fun to have
- if you can't post the WAV directly on this site for legal reasons, maybe you could try finding a midi of the song and posting it here

Good luck on it!