I was looking at the list of casual dining restaurents. I would pick the following based on atmosphere and quality of food;
Captn' Jacks at DTD - on the water, lights at night are nice, great food. Have the crab cakes, uber yummy!
Coral Reef at Epcot - when you book, ask for a seat next to the tank "cause it's a special occassion" (pick Anniversary, Birthday or Valentines Day)
My husband surprised me one year on my birthday - a diver came up to the window and pressed a 'Happy Birthday Vikki' sign up against the glass, very cool! Didn't cost a dime.
Happy restaurent hunting!