Best view is sitting in the Cantina in Mexico sipping a Tecate. You get to see
the show head-on
Best view standing, to me was from China.You are slightly off to the side, but very little vegetation is in between you and the water, so you can see pretty good.
Best romantic view is from France. You are looking towards the front of the park with Spaceship Earth in the background. When the fireworks are over and everyone is leaving, wait about 10-15 minutes. You can take your time walking back around the world to the exit. There will be less crowd,and you can appreciate the lights on all the buildings, and hear the background music from the various countries' pavilions. Sometimes in the day that gets drowned out...but it is absolutely relaxing at night.
I agree with above poster and add another spot for standing. Easier to show and explain. Look HERE See where it says showcase plaza and it looks like there are 2 huts on either side of it. Those huts are stores. Stand anywhere between there for an awesome view! We stood with my my mom, who in a wheelchair, last time we were there. It was just to the right of where I mentioned and it was an incredible view.
One BIG suggestion is to test the wind before you pick your spot. You do not want to be downwind of this show. It creates a lot of smoke!
Looking at the map that Mysteria posted, what about the bridge that connects France with the UK? Would that be a good spot to watch Illuminations from?
How long in advance do you have to stake out tables at Mexico to see the show?