A few thoughts on this issue:
1. What exactly is the purpose of the melee weapon? The model of home defense I work off of is to station myself between said intruder and my family with my shotgun. I have no intention of allowing him to get even close to closing the distance. While I suppose it is possible for him to do so, I doubt it is likely that you would encounter a grappling situation with an attacker unless you were attempting to 'clear' your house. I'd rather sit tight and let him come to me. In which case it's buckshot know question.
2. If someone is breaking into my house, non-lethal force is out as far as I'm concerned. I'm not gonna play games with my life or the safety of my family. The intruder forfeited his life when he came into my house. That means no stun guns, no pepper spray, and not batons. These are fine for defending yourself against and unarmed mugger, but someone with the guts to break into my house when I am home is to dangerous for me to chance it.
3. I now return to the main point of melee weapons and how to keep them around. First of all I don't like the idea of leaving tools around the house. Its great if I'm home but if someone breaks into my house it might actually give them a weapon to use against my wife. I personally think the most valuable weapon is the one you keep on your person. One more good reason to carry a pistol and a dagger or a good pocket knife too.
4. Tomahawks are terrible at close quarters. They are a power based weapon. It is very difficult to wield a tomahawk with power against an attacker who, based on the premise of this post, has already closed the gap so that your gun is no longer useful. I own a tomahawk and love it, but it is a distance based weapon. Once an attacker closes the distance it is a liability more than a help. Mostly because it is so easy to get a hold of the handle in a grappling match.
5. All things told, I have always used and continue to use a mid range knife. I use a 7 inch marine corp Kabar, but I wouldn't mind having a 10 in. bowie either. These are easy to use in very close quarters (i.e. quarters that are too close to use a pistol in), and very difficult to take from a man who is fighting for his family. Just make sure you have yours in a place you can get it out quick. A decent dagger isn't bad either just cause you'll have it on you and can get it out and take an attacker by surprise.
Just my thoughts... take it or leave it.
Owe one more question:
JTW, How much does a 6 foot redhead Irish attack wife cost exactly?