[@TheUnknowable] I think  it might be worth it to add more special locations to the list. A general idea of what major features of the underworld there are, especially how they separate the three regions. Is there a Great Wall of Tartarus? Do you need to get pass the velvet rope of Elysium? Does Charon have a major dock he lands at when dropping off souls? 

Another aspect that I would like to know is if the actions of the living when remembering the dead (i.e. the Day of the Dead, ancestral offerings, leaving flowers at a grave) have an effect on underworld inhabitants.