In the base game, there is one background that gives the player a horse and carriage. That is something that you normally hire at a location or you can get it through an upgrade to the HQ. Some of the "items" can have a very narrow usage perhaps. The horse and carriage for example could be of use if the players can get to the mystery location with that but if they need to take the train or a boat, then no. The apartment and the estate falls into the same category, I would give it the same benefits that an hotel rooms gives, but works of course only in mysteries that takes place nearby. Like most of the items, can be useful sometimes. Also, the so called "personal" items are items that define who you are, not always useful from a gameplay point of view.
“Thanks for noticin' me.” - Eeyore