From what I recall, only Jedi Masters were privy to certain information in the Jedi Archives. Anakin wanted access to those archives to find a way to prevent Padme's death.
Was that in the movie? Did the Jedi have a good reason not to let Anakin see even the info that could save Padme's life? And why was she in danger anyway? Don't these people have good enough medical care that death in childbirth should be unheard of?
Of course Palpatine was obvious to us, but I don't think he was the obvious choice for the Jedi.
The way he was hamming it up in the movie should have given it away to anyone who was reasonably adept at reading people.It wasn't really necessary to keep Palps' motives from Anakin for so long. Just make Anakin increasingly frustrated by the limitations on his power that the Jedi keep slapping on him. Power lust, not concern for Padme, was the right way to kick him to the Dark Side because it wouldn't require that we believe the Republic has FTL tech but medieval health care. Lucas overdid the concern that we'd hate Anakin, but he already blew that in the guy he cast. Instead, he should have cast an immensely likable actor which would have given him the leeway to write the character as less likable.
I don't think the part about the Jedi Masters having access to certain info was in ROTS. So when Anakin balked at not being made a master, it came off as him being whiny and overambitious. Before the events on Mustafar all Anakin's visions showed was her in pain, her dying. He didn't know how. So I can't assume he would think that medical technology could handle it. Padme might have been in a place without proper medical staff or tech for example. Plus, Anakin was still fighting a war where he was seeing lots of death constantly, so I'm sure he's aware of the limitations of medicine. And perhaps the limitations of any Force healing techniques.
Padme had to die to get her out of the way plotwise. Though I think the way she died could've been better. If I had had my druthers, I would've ditched the Queen/Senator storyline and made her a Jedi. In her attempts to stop or redeem Anakin, he cuts her down in combat, perhaps accidentally, but the wounds are fatal.
The way GL had Padme dying of a 'broken heart' was stupid. For one, it didn't fit Padme's character. In TPM and AOTC we saw that she was tough and that she was a fighter. She would never give up on Anakin, nor would she allow her children to be born, unprotected, in Palpatine's Empire. Two, GL kept trying to sell us on Anakin the hero even as he turned Anakin into Vader. GL pulled his punches and wouldn't let Anakin kill Padme, in a physical sense at least. As I said, I would've had it accidental, but still Anakin would've struck the blow. Maybe with Force lightning since we never got to see Vader do that.
I do think that GL erred in not making Anakin an anti-hero from jump, and having Obi Wan be the hero of the PT, its heart and soul.
About Luke in ROTJ, I think Hammil did a good job with the dark side seduction. I remember those naked looks on his face when Vader taunted him or as the Emperor tempted him, gesturing to the lightsaber sitting on his armrest. And when it started to shake. Luke wanted that lightsaber, he wanted to strike the Emperor down. I felt that, and eventually he gave in to it. Hammil conveyed that very well IMO.