I'd second the suggestions to maybe give some thought to what your wife's interests are in general. Perhaps building on that would help find a destination that would interest her enough to open her mind.

Do you and your wife travel much domestically? If so, consider the types of trips that interest her (beaches, cities, etc) as a starting point. If you don't vacation together much at all - if she's not into travel to begin with - not sure there's a lot of hope. I'd agree with suggestions of the UK, Caribbean, or even some Canadian destinations if that would help encourage her to get her feet wet.

My first time out of the country was at 16, to Spain and France for a high school trip. I was instantly in love with the idea of traveling the world the moment we got off the plane. Unfortunately it took until a few years ago to be able to really get to more places. Hard to put myself in the place of someone like your wife, since I would go pretty much anywhere and everywhere. Though as I'm quite smitten with Paris, I always put that out there as a suggestion.

Please keep us posted as to how things go, and good luck!

(btw it's been fun reading everyone's stories, too)