A 5th gate for me at the moment is not the right choice
3 parks need work, but i will concentrate on the one for me that needs the most work, but ironically has the most potential (at least in my eyes)
DHS
needs quite a bit of work, it needs the hat gone, the backlot tour needs to go, it is a shadow of what it was originally meant to be, but i like the idea of behind the scenes at the movies, but i would much prefer the essence to be spread over the park, so you are learning about some part of film making everywhere, in a fun way of course
Hollywood Boulevard needs the hat gone so that entering the park and seeing the theater is our curtain opening moment on your experience, the rest of it is ok as it it, a few minor changes to shops and whats in them (something themed to the park maybe, not the same stuff available at DD/DS)
American Idol and the Sounds dangerous theater need re purposing, my personal preference would be to turn the whole echo lake area of the park into a special effects area, so you could keep the Indiana Jones show, maybe re purpose one of the theaters into a cgi/high tech special effects sort of show and tell, then do it yourself area, lots of green screens, make your own movie scenes in small groups type thing. And re purpose the other theatre into more of an old school /traditional effects experience, maybe include things from the back lot tour in here such as set design and costume, along with sound effects and movie 'tricks' (forced perspective) would be even better if that could be linked in with the streets of America Area (ir even better swap locations for streets of America and the current Star Wars attractions
The muppets i like the show but to stick with the parks theme, maybe use the muppets to tell how the movies have changed from the 19th century to today, keep it funny have a big miss piggy number from the height of the musicals, sam eagle in a western etc and just have some of it 3d, gonzo and rizzo as our guides/narrators/
Keep animation courtyard much as it is, just updated as and when needed, and add in either the monsters inc doorcoaster or a fast paced ride to do with some kind of animation concept (i know weak). Probably also expanded the area use some of the old prop/studio buildings make it nice and windy somewhere that you have to explore like you would a movie lot, and make sure there is lots of bustle going on, get some streetmosphere in there
The lights mtoors action is a good concept, live action, another genre of film, but maybe just update it the show could do with a little TLC and get rid of lightning mcqueen, there is a whole animatioon courtyard, not all movies are cartoons, keep it as what it is
Sun set Boulevard not too bad as it is, maybe just change the beauty and the Beast show (frozen? i know its obvious but would be a good fit) this area would be the sort of finished area of the movie process with Fantasmic, and the stage show, along with the rock show (or at least backstage passes to it) and Hollywood royalty in the luxury hotel
I personally would build a new area, behind where current star wars is, and next to streets of america (would involving rerouting a road, and some water works, but in the grand scheme of things nothing major) for Star Wars, i would make it a large land similar in size to future land in MK, but it doesnt lall have to be filled staright away, there are three more major movies coming out, plus tv series, spin of movies, this is an area that can have an addition every couple of years, and would guarantee people would come and visit (not everyones cup of tea of course, but there are so many SW fans out there that it is enough) now this is where no expense should be spared, it needs to be heavily heavily themed, to the same detail as HP is or the fantasyland toilets are

, as for the setting that is where im not sure, part of me thinks it should be as movies sets, and be a bit like streets of america where you can see the bits behind, because that is the only way i can see environments like yavin, hoth, coruscant etc all working together in one area, but then another part of me wants them to just build endor for example and make the whole area one part, in terms of the land, there would be star tours obviously, there should be maybe a dueling coaster based on xwing vs tie fighter, put in a pod racer spinner, because it seems everywhere has to have a spinny ride for the kids, an area for concept art, movie memorabilia, sneak peeks of costume/set for upcoming movies etc a bit like one mans dream but SW focused, and i would go for a BOG type restaurant that is QS lunch and TS evening meal, along with some properly themed merchandise locations, with stuff you can only buy there, not all over the property. keep the jedi academy its fun for the kids and a good concept, but make it have a purpose built area