Wow, this is going to be a tough one.
My first choice would be dinner at the California Grill. if the park hours are out yet, see what time they have posted for fireworks that night. Most likely the park will be open late (since it's a holiday), so they will probably show Wishes at like 9 or 10pm. Plan on making a PS for around 7:30 or 8pm and ask for a table near the window. Then relax, have a great dinner and watch Wishes from either your table or if you finish before Wishes, then you can head out to the observation deck and watch them from there.
Second choice would be dinner at the Rose & Crown. Make it for 7:30pm and ask for a patio table. This way you can have a great meal, then sit back, have dessert and enjoy Illuminations from the comfort of your table.