You get to sit in a certain area for certain shows. I believe Aladdin was on the ground floor up by the stage when we went in 2005. The other shows (Muppet 3-D, etc) are again for a set area.
Not sure about the other shows, but Aladdin only takes the first 100?????? per show in the preferred seating area. We got in line too late (and we were there 45 mins early) & the line had been cut off, so we ended up getting in line with everyone else.