I say blow out everything from star tours to toy story aside from Muppets.
Install a monsters inc coaster in an expanded sound stage two. You could use the old corridors between the sound stages (2-4) if you wanted to be really creative.
Turn back lot express into the cantina.
Sounds Dangerous Evolves into jedi training academy.
Expand the endor theming that's in front of star tours all the way to sci fi drive in and expand Star wars into what was new york street. The new york street area would become the entrance to a rebel base where you would board a fighter and be launched into space (LIM coaster, Similar setup to Rockin roller coaster but shorter trains and a longer launch). The idea is you start in the base roll out to the "runway" and launch though the forest before being thrown into a upwards arc into space. The height of the building would be close to 150'. From there you would encounter enemies which forces you to spin flip dive and avoid enemy weapon fire. Having won the battle you hit hyper drive and "land" at a base on another planet. The beauty of this ride is the long launch and Hyper drive return. This keeps the ride profile low for a large enough area (most of new york street) that it would allow you to build another attraction over it.
Cars land would start around sound stage one and wrap around towards the Premier theater which is over by mama melrose. A version of Radiator springs racers would be placed over the launch area of the star wars coaster on the former new york street area. The cars land area would also be home to a new Cars themed Play area for the little ones and a few other small attractions. Lights motors Action would become an area for future development most likely sticking around rebranded as a Cars attraction. The beauty of placing cars land over the star wars roller coaster is the star wars ride building can be covered by the Cars desert plateau theming.
Muppets I don't know. Personally I love the theming but people just aren't as interested as they once were even with the new movies that came out recently. I think updating muppets 3D would be a worth wild investment (new 4 k projectors and new updated video) but I'm open to Ideas.
Back lot tour would not cease to exist but it would be very different. Backlot tour would go back to it's original starting place animation courtyard. The ride would start with going down stage lane to a drop off point where the water tank was previously for the prop building. Guests would proceed through the expanded building getting a guided tour then the guest would be picked up again at the old load area and proceed to catastrophe canyon. once they exit the canyon they would be taken through the wardrobe building in the reverse direction it currently travels and be returned to the starting point. Load and unload would be handled in the same location. Exiting guests could continue into the animation building or exit.
The Great movie Ride would get updated and there would be a complete overhaul of the munchkins and the witch. Several scenes would be replaced with different movies.
The BAH would be relocated outside the park entrance.
American Idol would be replaced with a comedy show Something like Whose_Line_Is_It_Anyway
Ok i'm done. It will never happen but man would it be cool.