Joyce,
From your question I gather that you are looking for;
- An arrival day dinner, presumably NOT in a park.
- A departure day dinner, either in a park or not
For your arrival day go to a fun and festive dinner. Some choices, like Hoop Dee Doo Review, may be a bit taxing on your transportation needs, since you don't arrive until 6 pm. Also I would choose something based on where you will be staying. But not knowing where you are staying, I would recommend the following;
- 'Ohana (Polynesian)
- Whispering Canyon Cafe (Wilderness Lodge)
- Spirit of Aloha (Polynesian)
- Raglan Road (Downtown Disney)
These have a bit more tempo to them, and while adult sons may find some a bit kitschy, they do get you all in a Walt Disney World frame of mind!
As for your departure day, and considering your clear love of international foods, you might again consider Raglan Road, but also perhaps;
- Biergarten (Epcot)
- Hacienda de San Angel (Epcot)
Another fun choice, to end the trip with a bit of humor and good down-home food, could be the 50s Prime Time Cafe (Hollywood Studios).
Write me back if you are looking for different kinds of suggestions, and I can refine my answers!
Have a magical (and delicious) vacation!