I agree with the PP, there are not good options for viewing from the restaurants in MK. I don't think you can see from CP. The Plaza restaurant is very good, but you can't see from there. The best viewing, IMO, is directly in front of the castle on Main St. You could grab counter service and try to get a table, but it can be tough due to crowds.
They have been doing Wishes Dessert Parties at the Terrace Noodle area, which would give you outdoor space. I have not done this, but not convinced that the viewing is that great. (Pics of the dessert look fabulous!)
To sit at a nice restaurant, try Cali Grille in the Contemporary. You have to time it right, tho. And you are not guaranteed a window seat, although you can request it.There is also an outdoor viewing deck, so if your table is not optimal (you will probably be able to see from most places), you can go out there.
Good luck and happy eating!!!! (And viewing!)