Friends and Family should have Access
A Personal house costs about as much as a Free Company House. 1.7 million, 13 million, and 35 million, these are example prices virtually identical to Free companies.
Permissions for access need to be fixed.
FIRST: The Bonding Ceremony of Marriage should most definitely grant use of all housing permissions with regard to things like Summoning Bells, Stations, House Foods, etc.
SECOND: An option that treats your Friends list the same way FC members are treated may also be a functional way of allowing a small group of people to make use of these multi million gil sinks.
Optionally: Giving Access to a particular Link Shell might also be a neat option, but I don't see that happening.