You will get a number of differing views on this, and all will have valid points. I will sum up the various arguments and responses I have seen with regards to HomeDefense guns etc during my research. I am picking up my 1st HD weapon tonight, but have spent quite a bit of time researching. Just some things to think about, there is much debate on what is the best, but really it coems down to what you are comfortable with..
Many recommend keeping the weapon on/with you at all times. This will do 2 things.
1. Your ready for an intruder at all times, no looking/remembering where your weapon is. Many will also recommend you keep it on your person with one in the chamber in condition 1. This is very much a personal choice, but the argument is: how usefull is the weapon if you get surprised and have to remember to rack one in the chamber, or pull it out of a desk drawer etc. You very well may not have time to do anything but realise the danger, pull the weapon to low ready and fire in a true emergency.
2. If it is on your person or right with you, you have control over it so there is no chance of the youngster to find or grab it.
If that is too much or does not fit your family/life then I would recommend something like a gunvault MV500. This is a electronic combination lockbox that can fit in a drawer or even be kept on the counter, or wherever you are. I would recommend having the gun inside in condition 1. This keeps it away from kids, but still quickly avaliable, though it will never compete with carrying your gun for speed. They also make a fingerprint reader version for faster access.
As you said it does no good to be in a safe, the lockbox is not much better than a safe other than you can have it out in the room you are in. Having it unloaded with the magazine out is not going to much slower than opening the lockbox if you practice opening it or use the fingerprint version.
I hope some of that helps, again I have no direct experience with this myself yet. But due to child safety concerns and research I have a MV500 for when the weapon is not on my person for some reason.