First off, this is where I am coming from: I haven't seen SGE in person, just in various videos from the net. I went on AE once. I thought it was cool and imaginative, not on the top of my list though. I WILL be going on SGE when I am there in Jan. I've kept an open mind and have heard arguments for and against SGE. My improvement ideas make the assumption that SGE will remain in the current, AE-like format and will not become a dark ride, etc as has been mentioned.
I think the first thing that needs to be fixed is the story line. Keep it as a prequel to the original movie. I think the whole escape to the Magic Kingdom needs to be scrapped. It's just not working and wrecking the storyline cohesion with the movie. More on what to do with it in the Main Chamber section later in the post. One thing that's bothered me is that even though it's a prequel, he refers to himself as Stitch, even though he is refered to as 626 until he hits Earth. I don't think he should refer to himself with I, such as "I'll get it" (reference to cell phone ringing). He should say "Me get it!", or something along those lines. It keeps more in line with his personality.
I think the first pre-show chamber is fine.
The second pre-show chamber is where we start to hit snags. It's mostly Sarge. I think they should re-voice Sarge. Get someone with a deeper, more commanding voice. Overhaul Sarge's personality. He seems waaay to flaky to me. His comments of "Tubey Things" should be replaced by something more technical. "Industrial Strength Polycarbonate Security Tube", or something along those lines. I also think the whole "Soiled myself" line just doesn't work. Drop it. I also think that Gantu should have a less "dominating" effect on Sarge. Make Sarge less submissive to Gantu.
Main show chamber: I think that up until Stitch makes his "Escape" things are good. Major flaws in the story line though. The 2 assitants mention "We gotta make it to the power grid". Instead of Gantu mentioning backup power, have him say "get that power fixed", and the others say "power back online sir." Also, are chilli dogs even sold anywhere near Tomorrowland? With the spreading popularity of the Turkey Legs, maybe they should replace the chilli dog with those. Keep the jumping part. When Stitch reprograms the teleporter, and Gantu says it's impossible, have Stitch say "Not for meee!", instead of referring to himself as Stitch.
This is where the story takes the most drastic twist: When Stitch teleports, have him teleport to a different location other than Earth (a different planet, etc.). Have Gantu say something like, "That's it, I'm going after him myself." Show on the screens a short scene of Gantu pursuing Stitch and eventually catching him. When Gantu has him in his posession, Gantu says something along the lines of "Well, I'm bringing him in. We'll let the Federation decide how to deal with him." This will tie it into the movie and set up the Federation Hearing Scene from the movie. Then Gantu will say "Recruits: Thanks for your efforts. Seems like we still have a bit of training left to do. Take the rest of the day off while we repair the teleportation chamber and I guess we'll have to try again tomorrow." Then have Stitch lick or spit on Gantu and Gantu responds "Oh, and get this thing some mouthwash, he smells like a <chillidog ,="" turkey="" leg="" etc="">(Turkey Leg, Chillidog, etc.). Gantu Out."
Those are my ideas for improving Stitch.</chillidog>