In order to choose one restaurant, it's important to know the context of this dinner. What is the occasion (i.e. how special is it? there's a big difference between a proposal and a birthday)? Who is it for? Are there any special dietary needs or preferences to consider? Some restaurants will handle that better than others.
Blue Bayou: the food here can be fine, not great, but the atmosphere can't be beat if you want the experience of dining inside POTC. Plus, you can do a F! Dining Package here, so you would get a sort of dinner-and-a-show experience.
Carthay Circle: nicer meal than BB, better staff overall, pretty rooms, alcohol served here. Better options for vegetarians and vegans -- note these needs on your reservation and speak with a chef if needed. If you time your reservation right, you might be able to dine while viewing PTN and the fireworks from the balcony.
Catal: food is fine, but we don't consider this fine dining -- more like casual-nice. If you dine upstairs on the patio or by the windows looking across at what used to be RideMakerz/BAB, you'll see the fireworks -- very nice way to enjoy dessert.
Napa Rose: one of our favorites at DLR, where we get the best service (we are regulars and the staff knows us), very accommodating with allergies and dietary needs. NB: no AP discount here. We've never had an experience like the one mentioned above, but whenever there is a glitch of any kind, we make sure to mention it to our server and the manager so that whatever needs to be remedied can be fixed for future guests.
Other:
Steakhouse 55, if you like steak.
The Jazz Kitchen can do very nice meals -- private rooms are available, too -- and the live music can be very nice. Good people watching from the patio and balconies.
Off property, but nearby: The Ranch -- very nice steakhouse with excellent wine list