As mentioned before, we're letting the cats outside now. It's been almost a week, and the results so far are good. The cats don't seem to roam very far - which is comforting. They appear comfortable outside now - not quite so jumpy. And, more than not, they hang out inside the house, or just outside the sliding doors - when given the choice.
The bonus feature is that they're usually too tired to run around like little banshees in the middle of the night - so Mary has been sleeping solidly through the night (I always do).
Now we just have to wait for the time that one of the kittens doesn't come in for the night.