My suggestions would be The Brown Derby at MGM. It is the most upscale restaurant at MGM. The others are high on concept, low on romance.
At Epcot, perhaps the Coral Reef restaurant which has huge windows for aquarium viewing. If you luck out, you can get a seat right next to the windows...try for the earliest dinner ADR for the best chance. The food is good, but not necessarily memorable. In the World Showcase, I would think about the Bistro de Paris. It is upstairs and less hectic than Chefs de France....