Wishes:
If all you want to see is FIREWORKS, you can stand at MOST areas in the MK.
(And a wide variety of places OUTSIDE the MK.)
But if you are NOT at CERTAIN SPECIFIC LOCATIONS, you will MISS the "full impact" of the SHOW called "Wishes".
Wishes has two fireworks "STAGES":
One fires its missiles from a location FAR BEHIND any public area of MK.
The other fires its missiles from the ROOF-TOPS of Fantasyland/Liberty Square/the Castle.
The guests' VIEWING ANGLE will affect "if and how" these two stages can be viewed together (they are designed to be viewed "together".)
There is a full AUDIO TRACK that is synchronized with the fireworks.
It is the "motivation" for the unique fireworks effects that change with each MOOD and SECTION of the audio track.
The audio, and positioning of the two fireworks "stages" relative to the viewer will affect the impact of the show.
The front of the CASTLE ITSELF is part of the "show".
There is an elaborate lighting system that is used to change the color of the castle to suit each MOOD, and even "textures" and shapes are projected on the castle at key points in the show (Mickey's Sorcerer's HAT is a great one).
Tinkerbell's flight (which used to take place PRIOR to the old fireworks show at MK) is now WITHIN "Wishes". She doesn't fly EVERY night, but she OFTEN flies and you should be in a position to see her.
The SWEET-SPOT for Wishes is: starting from approx. the "bridge to Tomorrowland" ...on up Main Street to the "Main Street Cinema" (Pal Mickey Store).
That is simply the "optimum viewing" area.
There are MANY other places to watch, but they are all compromises that diminish the "full effect" of the show in one way or more:
Some have little or no SOUND.
Some have obstructed views of the fireworks.
Some only allow viewing of one of the two fireworks "stages".
Some places (like the Main Street train station) don't turn off the lights in the area, so there will likely be lights in your field-of-vision.
Some don't allow a view of the castle-front and/or Tinkerbell when she flies.
So, if you don't MIND this, you can choose from a multitude of "viewing spots" throughout the MK.
My point is that the show is designed for "FULL EFFECT" to be seen from the "Sweet spot" areas I described. (But, yes, those can be C-R-O-W-D-E-D!)
Many view it from near the dock for the paddle-wheel Steam Ship in Liberty Square.
Some watch from the bridge that links the main Frontierland street to Splash Mountain.
Some find spots to sit in other areas of Liberty Square and Frontierland.
All of these areas offer a good view of many/most of the effects, but not all... and certainly not in the "foreground-background/dual-layer" manner in which the show is created.
I will tell you where NOT to view it.
No matter how TEMPTING it may appear before the show:
Do NOT stand on the sidewalk between the Hub and Frontierland,
or on the sidewalk between the Hub and Adventureland.
Trees nearly totally obscure the main larger fireworks, and the audio is (most-likely INTENTIONALLY) MISSING (no speakers) in these areas.
Also, the upper level of the Main Street train station (a great place to see the "SpectroMagic" Parade) is a tempting but BAD choice for "Wishes".
They DON'T turn off the LIGHTS on the last few buildings on this end of Main Street (or on the train platform) during the show, so the lights are in your eyes the whole time.
Here are some shots taken from a video camera that I used up there one night. Note the flag-pole dead-center and the gleaming lights of Main Street.
Another "ought-to-be-GREAT-but-ISN'T choice is from the "Noodle Station" seating area (the open-air counter-service restaurant that's between Main Street and Tomorrowland).
Not only do they NOT turn off the lights here (and the sound is not clear), most of the fireworks are hidden from view by the roof of the restaurant and/or the large PYLON that's on the bridge to Tomorrowland.
(I will say that there ARE a very few spots in this restaurant area that DO offer GOOD unobstructed views, but you MUST be in those exact spots and not mind the ceiling lights being on and the lack of good sound.)
Wishes is the only fireworks show that can be (for the most part) seen from outside the presenting park.
Good viewing can be found at the beach of the Polynesian Resort (walk along the sidewalk there until you see a view of the castle unobstructed by trees.)
The Ohana restaurant at the Poly offers good views (and they pipe in the audio of the show). Same goes for the California Grill Restaurant (and outdoor terrace) at the Contemporary Resort.
At Grand Floridian, "Narcoossee's" is the restaurant with the MK and Wishes views (and sound).
The MK parking lot (TTC) offers views, as well as do other outdoor spots for several miles in any direction of MK. But without the sound, you miss a lot of the "show".
Best analogy:
Sitting across the highway from a Drive-In Theater and "watching the movie" with binoculars. You can do it, but it LACKS something.
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IllumiNations:
Great viewing from:
Bridge between UK and France (under this bridge is where the so-called "IllumiNations Cruise" boats view the show.
The plaza area on the water (lagoon) at Italy.
Near Norway is prime.
Area to left of UK "Rose and Crown Pub" (this is also near a roped-off Wheelchair viewing area.)
Front area of WS near the "twin gift shops" (very crowded here). Many times guests are asked to SIT on the pavement so others behind them can see.
Actually too many "good" spots to list.
Just remember that you don't want to stand under tree-limbs (obstructed sky-views) or DOWN-WIND of all that fireworks fall-out and SMOKE.
"Outside the park " viewing:
While "Wishes" CAN be seen and enjoyed (for the most part) from many places outside MK, IllumiNations is a different story altogether.
MOST of effects of IllumiNations take place ON (or just a few feet above) the surface of the water of the WS lagoon.
Except for the very first "Comet" firework effect, and several other major "sky-blasts", IllumiNations can't really be enjoyed from outside Epcot's World Showcase. A good 1/3rd of the show does not involve fireworks but a large "video-globe" towed across the water and tiny lights imbedded into the buildings of WS.
One favorite outside spot to view the few "sky-blasts" is on the bridge coming toward Epcot's International Gateway from the Boardwalk Resort. You can't hear any of the music track, which is a very important part of the show.
You can't see very much either, and there will be very long periods of time where you see nothing at all.
There are a few villas at the Boardwalk that have (obstructed) views, and there are limited views from a beach at CBR, but as stated above... you will not see very much, and what you DO see can't legitimately be called "IllumiNations."