So, for personal housing...
Personal housing will probably be expensive so I would like to suggest for SE to emulate the real world :D
Allow us to take a bank loan to buy a house. Then, every dungeon run we do gets 10% of our gil earned taken. If we miss payment, make us pay more interest. And if we miss payment for too long, get a Yoshida NPC knock on our personal house and demand payment. Also, allow us to mortgage and rent our houses to earn gil.
Also, allow for joint ownership of personal houses for "eternal bonded" couples. And if they get a divorce, we can start seeing a quarrel over who gets the ownership.
Yes, I am not being serious. :p