Why didn't I think of this sooner?
Actually why didn't I think of this at all? We just implemented nested stamp and key plan families in our title block families. I wish I could say it was my idea, but as is usually the case one of our power users suggested it.
I love things that make our lives easier
All we did is create place holder annotation families for a stamp and a key plan. Then we nested those place holder families into our standard title block. Now when people want to add a stamp or key plan all they have to do is edit the nested family, reload it back into the title block, then load the title block into their project. All the visibility parameters are already assigned so people don't have to worry about if they're that step. Because let's face it. People forget that step, and if you forget that step you get nothing when you flick the visibility switch.
It's the little things. Actually this one is huge!