Wow. This is a really weird question, because a lot of people live with family members in their house anyways, they just don't segregate the floors/rooms/what have you.
Um, first off, any room can be made a "lock yourself in" type of room if you have a little bit of money, some time and a small tool assortment.
Cell phones have done away with the whole need to run a hard phone line to the armored closet thing. Cell phone, built in texting, GPS, some even have live internet connections. Plus, you don't have to worry about an enterprising person pulling your power meter on the side of your house, killing your answering machine, cordless phone charger and basic household powered units to allow multiple communications at one time, like a cable modem/router or a DSL unit.
Now, I have played with an "RF Identifier" a few years ago, that basically over rode the signal of a common cell phone carrier with another larger carrier with a footprint to stamp out others to allow, say, a movie to be watched without some jackass talking about where the party is it. It worked great at the time, but that unit won't work worth a damn today because of the change in freq's. You need an expensive one now to be able to drown out the new cellphones. Plus, they heat up like crazy and have limited "blocking" range. Plus, they are now illegal as hell... LOL If you are dealing with someone that has one of these, you are going to be in trouble anyways, because they are prepared.
Next, all you need is a bottle neck. Anything will do, but the better chance you have of "covering" one place, the better chance you have of defending it.
If I am in a room with one door in/out, like a bathroom, and it has a small, second story window to allow the venting of air, but is kind of small and hard to get to, chances are good, if you want me, you are coming through that door to get me.
It doesn't leave me anyplace to run, but if I have, say a 12 gauge and a handgun with some extra ammo, how long are you willing to take to get me before the police show up? How many bullet holes are you willing to risk getting in you?
Yeah, you could pull some crazy Terminator crap like coming through the wall, hoping you don't ram your T-1000 arms into the 2x4 wall joices, but I kind of doubt you are going to do that with your first strike attempt.
Recently we built a brand new Federal Reserve Bank that will process all the money shipments for the local banks here in the Seattle area. New money comes into the FRB, then non-discrete carrier trucks take it out to banks. They return with money to be destroyed. Repeat.
Well, they Engineer these things pretty damn hardcore. This thing wil handle a spec'd 10.4 Earthquake and be able to open and remove the cash inside within minutes of the 'quake being over. Needless to say, security is off the charts.
Before it was done, I went and did a Q/C walk through with a couple of guys from the site. My "official purpose" was to inspect the work done by my crews and make sure we met contract standards. My reason was to see what goes on inside one of those places... LOL
Everywhere you go in there, there are choke points. You turn to go down a hallway, the door at the end is a choke point. You bring a cart with you to load money, there isn't room for you and the cart, to be side by side to get to the access card slot, so you have to pull the cart to the doors. Or you need two people. The front dude is dog meat the minute that door opens. There is about 10 to 12 inches different between the carts they use and the width of the doors/halls. They don't have exposed jams like you do at your house. The door is part of the walls running down the hallway and all the doors inside are steel pocket doors, so the door is braced by the wall itself. You can't bash it in, well, you can but...it will cost you time, and bodies. There are firing slits EVERYWHERE. Gun ports with locking cylinders for one way shooting. Vents up off the ground, pointing down into the hallways, where you don't even have to look, you just stick the barrel of an M4 into the hole and open up. It's ugly. It would be a blood bath...
There whole goal isn't to make it impossible for you to steal the money. Their goal is to make it so costly for you to attempt it, that by the time you are done, there isn't any of you left to actually spend the money.
The same can be true for your Safe Room. Your goal isn't to live there forever. Your goal is to get to the other side of a choke point and make the motivation of getting whatever it is you have ( your body, your money, your very blood in the event of Vampires ) so off the charts costly for anyone wishing to try and take it, that they think better about it and leave before they can get it. Or die trying.