First things first... CONGRATULATIONS !
Next - if you are staying "on-property", make sure you leave them know when you "Check-in" (or if you make your reservations over the phone or on-line, tell them !)
Now... for dinner:
No doubt that the "top-of-the-line" (IMHO) is "Victoria & Albert's", but it can be pricey, and sometimes hard to get a reservation (again - if you choose "V & A" and you call for a reservation - TELL THEM !).
The recommendation of "In-Room Dining" also is a very romantic option, depending on where you are staying.
After that - it is what it is...! after all, you are at Walt Disney World ! I would suggest, in this order (again, IMHO !)
3) Yachtman's Steakhouse [Yacht & Beach Club Resorts]
4) Citrico's [The Grand Floridian Resort]
5) Artist Point [The Wilderness Lodge Resort]
6) Shula's [The Dolphin Resort]
7) Narcoossee's [The Grand Floridian Resort]
8) Paradiso 37 [Pleasure Island/Downtown Disney]
9) Flying Fish Cafe' [The Boardwalk Resort]
10) Le Cellier [EPCOT - Canada]
11) Bistro de Paris [EPCOT - France]
12) The Brown Derby [Disney Studios]