There are GAC at DLR and I just saw a recent thread by lalamama on this topic. We didn't get one, since DH was in an ECV and that's visible enough to serve as a GAC when necessary. I just wanted to post re: Aladdin.
DD5 and I went to Aladdin first to stand in line about 45 minutes beforehand. However, the lines were so crowded in the initial waiting area behind the "false front" theater area that when DH came with DD2 just 5 minutes later, he left his ECV out and hobbled in on his cane (otherwise there would have been no way for him to join us as there were another 50-75 people behind us streaming out the doors. Leaving the ECV was a BAD MISTAKE. Not only did they make us wrap around another huge line area once they moved the bollards/ropes by the fake theater part, but he had nowhere to sit and rest.
We went so early that there were no CM to ask. I would definitely ask someone if there are any accommodations for Aladdin like waiting on the side and going in with the Preferred Seating people. They didn't wait at all, as I saw folks stroll up 5 minutes before the show and walk right into the theater as we waited outside still. I thought they'd allow 15 minutes for us to file in before the show "start time" but I guess that start time is just when the general audience is allowed in.
FYI, I saw a girl in a wheelchair and her parents just pushed her in the regular line. if DH and DD2 had been with us in the first place, that would have worked as they have very wide lines once you're in the open air part (not just waiting in the crowded "fake theater" part).
Hope this helps!