Depends on the mood of the group.
If they are fun loving don't mind a little ribbing, and have hardy appetites, I would suggest 'Ohana.
If they like a more sedate meal with all the trimmings, and cost isn't an object, then I would suggest The Yachtsman Steakhouse at the Yacht Club.
One right in the middle for a large group would be Mitsukoshi Tempanyaki in the Japan Pavillion in Epcot.
Or if they are more daring and wouldn't mind a bit of entertainment in the way of Belly Dancers, then Restaurant Marrakesh in the Morroco pavillion in Epcot would be alot of fun.
Whatever you decide, you really can't go wrong.
Have a great time!