What a great opportunity for you both!
Disney is such a different place when parents are there without their little ones. Just the prospect of an hour of window-shopping, amongst the CRYSTAL, is enough to send shivers up my spine...
Consider staying at a resort which puts you closest to your favorite park. They are all kid-friendly, but many have hidden gems that are perennial favorites of adults.
Consider fine dining at a restaurant which might be out of your comfort zone with a larger party; with only the two of you, it's much more manageable. My family has never experienced The Hollywood Brown Derby at Hollywood Studios, but I make it a point to dine there with other chaperones while on our Senior Class Trip. The Cobb Salad is unlike anything I've had anywhere else and Raul makes a gorgeous Arnold Palmer!
Furthermore, the kids love so much about the countries, but it is so different to really linger at each country's shops, indulge in the food and beverages, and chat with really sweet Cast Members who call that native land home.
Another consideration is spa time!
Saratoga Springs Resort and Spa is a full-service spa which offers many relaxing treatments...and you have no one to worry about but yourselves on this trip! Massage or facial, maybe?
Of course, if there's a "chic flick" (or other film the whole gang doesn't want to see) consider catching a movie at
Downtown Disney's Fork & Screen, where a great full-service menu awaits, along with adult beverages.
No matter what, you're both sure to have a blast with just the two of you at Walt Disney World! Enjoy!