This is my first car with a Nav and from now on, I will always get cars with Nav. I use it all the time to find restaurants, banks, hotels, etc. Finding a Starbucks should not be a problem. Just learn how to use it before you show your wife how it works. It would suck if you were trying to show her how it works and you yourself are not sure how to work the menus.
I'm sure she will grow to love the Nav as my wife did. She too was reluctant to pay for it in the Bimmer but now, she wants one in her car.