Unfortunately, none of the restaurants that have a view of Wishes will guarantee you a table with a view when you check-in. Many/most will allow you request a table with a view, but none will promise that one will be available before the fireworks start. In most cases, I would plan on having to go to the observation area (if the restaurant has one) or to be done before Wishes starts. California Grill has an observation deck for guests that are seated at a table without a view. Guests at Narcoossee's go out to the veranda to watch Wishes (some tables have a view, but that view is often blocked by guests out on the veranda). These are the only two places where guests are pretty much guaranteed a place to watch Wishes (i.e., the servers expect guests to go out to the veranda/observation deck and will help time the meal). Being Signatures, I would allow between 90 and 120 minutes for dinner.
There are a handful of tables with a view at 'Ohana and Citricos, but neither place has an alternative viewing location for guests without a view. So I would plan to finish up dining before Wishes start in case you end up at a table without a view. The other restaurants at the monorail resorts do not have any sort of view and you'll need to eat before or after Wishes. The Contemporary has the 4th floor observation deck for guests to view Wishes. The Poly has the beach (not sure about access and the view now that the DVCs have been built). The Grand Floridian has the boat dock area.