While we have yet to see, we know it's a projection and laser show that will be presented on Main Street, it's a small world, and Rivers of America. I'd hazard a guess that a great spot could be somewhere toward the front to middle of Main Street so that you could see the length of Main Street projections. I'm guessing the Small World mall, closer to the attraction would be another great spot. Having seen projection shows on Rivers of America, I'd expect it to look good there, too.
Without fireworks in the show, I think as long as you can see the expected projection area, it's all about comfort in choosing where to watch.