Standing behind the castle, to me, is just as awesome...if not more awesomer than standing in front. The fireworks are closer and and all around you. And the area is a little more empty because everyone is always clamering to get upfront. I got stuck behind the castle by accident once because I was leaving Mickey's Toon Town Fair and heading out of the park; however, they roped off the exits around the castle and we couldn't leave until after the show. It was the coolest thing I had ever scene.
Another cool thing you can do (and yea...this may get me expelled out of here, lol) is hop on the Monorail to the Polynesian. Get a snack at Captain Cook's and see the show on the beach. I will be there that week as well and it's my home hotel when in The World. Sooooo much nicer than dealing with those psychos in the park.
Another thing you can do, if you time it correctly, is to take a ferry/Monorail ride around showtime. Then you can see the fireworks on the water or from different angles of the Monorail loop.
I honestly can't deal with the people anymore. They are so rude and ignorant! And this is coming from a 33 year old, lol The parades are the worst. If I feel the need to see the 9PM parade, I watch in Frontier land. the people on Main Street act like you are going to rob them or something if you dare try to squeeze into any spot near them.
I remember last year, I was walking with my little cousin on our way out of the park. It was our arrival day, her mom wasn't feeling well after dinner at Be Our Guest, so I stayed with little cousin in MK while her mom went back to the hotel. Though she was having fun, by 8:30, she was ready to head back home. Main Street was, of course, cluttered with people; all the sidewalks taken; it was a mess. There was one gap between to people and I pointed in their direction, telling my cousin we can go through there (in order to get ON the side walk to get out of the park). Well, the family just moved there hands into the gap and yelled (YELLED) that the spot was taken and we couldn't sit there. My cousin was a little upset (she doesn't like to be yelled at) so I very sternly spoke back, "we are LEAVING the park and need to get on the sidewalk. EXCUSE us!" I then pushed through them and went on my way. It was unbelievable.
Anyway, If I really need to see the parade (I do love it), I wait until 11pm. Then I can see the show anywhere I want on Main Street. Whenever I am at another park but MK is open late, I always come in around 11 and have my choice of seating for the parade. All those sidewalk hoggers at 8 are idiots. sorry. I am getting mean, lol
ooops! sorry...end rant....
My main point is: There is a lot of places you can see the fireworks if you are willing to think outside the box and you don't care if you are not in front of the castle.