I feel it would be realistic that your character should be able to clear out an abandoned building or occupied one and have the ability to be set as your default home. Buildings fit for your home could possibly be things like and old military base, abandoned shacks, gas stations, and the likes of it. Now to make this fair, large buildings like the casinos in NV or something like the Pentagon back in FO3, would be too big, and unfair to use as a home.
Now to claim these homes as yours, you would have to do something along the lines of the follower terminal at the Gun Runner's shack. Only a set number of homes would be able to be set as your own home though. It's hard to explain but like the concept of only a few candidates in Skyrim, legible for recruitment into the Blades. Only certain homes in the game would be allowed to inhabit.
For customization, say you want furniture or to get the grunge like feeling away, a company could be found in one of the cities that can take care of this. They would be able to place objects like metal boxes, ammo containers, and the likes of it within your home.
Now on a separate note, the home could have more features like The Sink. By this I mean that we could possibly find upgrades for the place around the wasteland, and have things like an auto-doc or special lights.
Now, on your pip-boy, there would be an option somewhere to fast travel to your home. Another option would be so you can actually set the home as your "default" home.
So what's your opinions on this? I know I wasn't the only one to think of this. Can I see your input?