Here are my ideas:
A New Hope:
Lightsabers need to be re-done. When Luke firsts uses his fathers lightsaber in Obi-Wans hut its so... tacky. It looks so fake in comparison to the Prequel Trilogy, and it isn't the same colour they used for Anakins in Revenge of the Sith either IMO. Also the sounds don't quite sound... in the room. They sound too much as if they've been placed on top of a recording where as in the Prequel Trilogy you really believe they're making those sounds.
Also, Blasters need to be redone. If you updated the lightsabers you might aswell update blasters. Also another thing I noticed in the Original Trilogy everyones blaster-fire is red, but in the Prequel Trilogy the "bad guys" had red lasers and the "good guys" had green and blue lasers, similar to the colours of lightsabers. So I think the weapons IMO could all have updates. Another change that could be made is maybe some silver added to Leia's gun she has right at the start, it looks really old and cheap as all black and I'm sure for that small scene in which she uses it, it could be digitally recoloured.
Vader ordering Beru and Owen to die, I think that there should be a little scene before Luke returns home where a Stormtroooper comunicates with Darth Vader and tells him that they've tracked the two droids back to a location (Lars Homestead) and then Vader orders the death of the two.
In general all Planets/Backgrounds, I could really tell which planets backgrounds etc; had been digitally enhanced because they looked fantastic but in some of the places we visit you can really tell they're real locations and don't have the Star Wars "unreal" feel. Like on Coruscant for example we have ships constantly flying past. I think we could have a few more creatures/things going on in the background and have more ships occasionally flying about.
Alderaan, I think an actual scene of Alderaan should be included. This is Leia's home planet, we see where Luke comes from and I think we should see where Leia comes from and what the Death Star actually destroys. All it would have to be is a short scene of maybe Bail Organa and Queen Breha Organa sitting out on a balcony looking out into the sky and then Bail Organa could say something like... "I hope Leia's alright".
The scene where Han Solo is greeted by Jabba the Hutt is good as it is but when we see Return of the Jedi we instantly notice that Jabba is a puppet/costume for this film as the CGI one looked different. If the colours could be changed to match it at least that would be great. Also I noticed that in a few shots Han's eyelines don't match up with where Jabba is whatsoever.
If possible Darth Vader vs Obi-Wan Kenobi could be changed up a little. In Revenge of the Sith we see such an epic duel on Mustufar that this one doesn't really reach climax. This is also the first time we see Darth Vader in combat, now we're supposed to fear this guy and he's supposed to be all strong but the fight he has was good in it's time but now looks a little... weak? I know we can digitally edit faces onto figures since Count Dooku was mostly a stunt actor with a digitalised face so I think it is possible.
Empire Strikes Back:
Lightsabers and Blasters - see A New Hope post for reasons! ^
The whole Hoth sequence could really do with some improving. The setting was filmed in a blizzard, it looks great but it is sometimes a bit too much and you're with alot of white-screen for sometime and it gets boring. Also when the Hoth Rebel base is under attack the camera just appears to shake and wobble which looks really amature, it doesn't look like the base is under attack it looks more like the camera guy was drunk. You could easily include some CGI attacks on the base like when Han and Leia are runnining and the hallway collapses maybe we could get a shot from outside of Stormtroopers bombing the base to cause that explosion. I mean, just little niggles that would touch it up a bit.
General Special Effects, and this goes for A New Hope too, when someone shoots someone in the Prequel Trilogy they fall, or when they shoot a wall it crumbles and briefly smokes. In the Original Trilogy there is alot of sparkes and snap, crackles and pops. Also there is alot of smoke to show where blasters have hit. It looks all too, school production-ish where you've only got a smoke machine and CD-Player and you're trying to create a battle.
Return of the Jedi:
Lightsabers and Blasters - see A New Hope post for reasons! ^
We could include Boba Fett escaping certain death, we hear him have a stupid scream in this film when he falls into the Sarlacc, which he wouldn't make if he lives. After Han/Luke/Leia all escape Jabba and fly on the barge to safety maybe we could see Boba Fett crawl out of the top of the Sarlacc pit and sort of have some cliff-hangar as to what happended next and leave some future troubles in childrens imagination. We always like to think there is still evil out there and that Leia and Lukes adventures aren't over and this could be a way of creating that.
The Battle of Endor really needs to be updated, and pretty much all the Endor scenes. We haven't really visited woodlands before in Star Wars and when we do they're too close to real life, I think we should have creatures lurking in the background and maybe fog once and a while. The Speeder Bike chase with Luke and Leia looks really bad background effects, they could be updated and I think the actual battle itself could be more climatic. We could have some Rebel Soldiers commanding and fighting, also maybe we could see a helmetless Stormtrooper giving orders, throughout the Clone Wars we see them without helmets, why not now? Also this scene could do with losing the "toys" falling over etc; and have some computer generated enemy machines.
Another general Special Effects one, Darth Sidious' Force-Lightening looks frail and weak in comparison to the stuff we've seen from Dooku and a younger himself in the Prequel Trilogy. If Luke is crying in agony and it's enough to turn his father Darth Vader back and kill Sidious then we need some mega special effects that show true torture for Luke to endure.
Another one could be Leia actually seeing the Force-Ghosts of her Father and Obi-Wan Kenobi, she seems to see Luke looking at something and goes over and sits with him but never actually takes notice of the ghosts standing right in front of her, maybe some digital glances might be nice, otherwise she looks totally unobservant, and I'd like in the celebration scene to see some old faces like when we hear Jar Jar Binks say "Wesa Free!" maybe see a shot of him celebrating with Gunguns and Naboo people, maybe a shot of a very old Sio Bibble with Queen Kylantha.
Anyway, I know Lucas will never do any of my requests, but I'd love the man if he did. I'm a child born into the Prequel Trilogy and I don't really see the big deal of going back and editing good films to make them much better. They don't fit with the films that are supposed to be years before them, which makes it seem like the technology of Star Wars decreases as they get more into the future, which in the world we live in is the opposite way around.