There are so many possible bells & whistles around GTD that it can get confusing, overwhelming, and even set you back... The diamond in the rough with GTD is the simple thought process - the "nugget"...
1. What's the desired outcome?
2. What's the next action?
You will need to read the book and/or supporting materials from GTD Connect to really understand why this is the nugget, but if you get lost, just keep coming back to ground zero!
Oh, and don't expect that your implementation and your wife's will look anything alike. And resist the temptation to tell each other you're doing it wrong!