Good ideas 5x5. I take my wife out for pie at Lindsay... She likes that. Planning on a leaf tour in the fall, I figure that will be pretty, and she will enjoy it.
If you can, plan on taking a few friends along too for a flight, that way their enthusiam tends to rub off on your partner. Its hard for her to be down when the passengers are all upbeat and going..."This is so cool."
I also have my wife do lookout for planes. Keeps her involved, makes her feel like she she is contributing, plus she is really really good at it. She is too nervous to put her hands on the control column for long, I think she believes that the plane will instantly fall out of the sky.
Not sure what the real secret is. But my wife has been better than I thought, and I have likely given her some of my worst passenger'd landings. I guess in the end, its about building trust, and them meeting you half way on something you love doing.