I don't lock my doors when I am in the house, but my wife does...
Doc-
A gun for self protection may not always be the best choice. A gun only works if you are there to use it, if you are willing to kill, and if it is loaded and ready...and at hand. For homes consider web cams and a monitored alarm system. Alarm and tracking system for your car.
A loaded and ready weapon presents a danger if children are around, or curious teenagers-- or even angry spouses or drunken friends. We have racoons up here in the mountains... I wouldn't recommend one to someone who has trouble controlling their temper either. And if you are nearsighted like me, you probably couldn't hit the bad guy anyway. It is also one thing that burgulars look for in homes and will actually scout out signs of gun ownership like NRA stickers on cars- since they normally B&E when you are at work.
At least in my state (CA), you can't shoot someone for trespassing. You can't really shoot them for threatening your property either- only your life or safety or the life of someone else ("...and try to harm" is the operant terms here). You can't shoot them when they are running away. And you can't have loaded and ready weapons in your car or concealed on your person in most public places.
Especially if you live in a place like Washington, if you have a big piece of property, you will have lost hikers and armed hunters wandering across your acreage. My sister and her husband up in the Tiger Lake area always have the unexpected visitor, and always treat them kindly.
The safest way to store firearms- unloaded, trigger lock, safe- ammo locked separately- makes their use for self defense a bit impractical-- unless your local lowlifes are rather patient.
If you train with a fire arm for self protection, they will probably teach you to "shoot to stop." That means a minimum of three rounds if not the entire magazine in the center of mass. You don't shoot to wound, and you generally don't shoot to kill. The decision is irreversable and permanent- whether it was truly a lowlife crackhead intent on some harm or a lost and slightly drunk Japanese exchange student, he will be lying there with your lead in his ten spot, bleeding out on your driveway and you will have to clean up the stain and live with the consequences. I would much rather pepper spray the perp and sort it out later, or scream like a girl and let help arrive, or at a bit more risk apply a wrist lock- arm bar and hope for the best.
I am 41 years old. I grew up with guns. I may be very luck or very blessed. I grew up in the worst neighborhoods in East LA and worked in downtown at the produce market when I was 14. I also worked at a couple of liquor store as a kid all the way through college. I taught in inner city schools for 19 years and there was not a single instance where a loaded gun would have been useful that I can think of. I can think of a few situations where one would have ended up getting me killed.