I've always thought that Luke's need for more training wasn't to learn how to access the Force, but how to control it. It was more the issue that Luke was still a reckless kid who was still largely driven by his emotions. And of course Yoda wanted to make sure Luke was emotionally ready before confronting Vader and learning that he was his father. The fight with Vader ironically helped him develop that emotional maturity, he had the biggest shock and defeat of his life. As much as creating a Lightsaber was a sign that he'd learnt both the technical skills required to design a lightsaber and the control of the Force necessary to construct it. I think the time was mostly spent getting his head on straight, training the skills he'd learnt from Yoda and working his way through Ben's Journal. Shadows of the Empire implies he spent a lot of time working on his Lightsaber and getting his head right.

For Jedi and Power I'd have to say Luke, though I'm not sold on the wisdom/intelligence. There Yoda probably gets my vote. Sith it's Palpatine all the way, he had everything, both in terms of power and intellect, the guy not only led the Jedi and Senate around by the noses, but he managed to win over Dooku, who was himself considered one of the most powerful and intelligent of the Jedi of his day. In short the Emperor had it all.

By this point I'd be hard pressed to find any one thing. Top two? I'd probably have to say either the Vong, or Boba returning, say what you want about the Jedi vs Bounty Hunter thing (I'll admit I lean towards Jedi since that's the tone GL seemed to set before he sold his vision for insane amounts of money), but Boba really never seemed to put up that much of a showing in the films. I mean his big claim to fame was managing to trap Luke with that rope, which while impressive is made less so by A) His inability to close the deal and B) The fact that Luke had his hands full with a bargeful of people trying to kill him.

I've always taken the OT as a single entity, I can't remember the last time I haven't tried to put aside to watch all of them as closely together as possible. For my money they build upon each other. As for the prequels, I've never much cared for them. What I loved about the Original Trilogy was the characters and the feel they gave to the story. The characters in I-III seemed lifeless and based more upon the epic CGI battles and lightsaber duels. While the battles and duels had been vital to the OT as well it had been the dialogue and revealations that drove them for my money (Kenobi sacrificing himself, Vader telling Luke he was his father and Luke coming so close to the fall to the Dark Side in his battle with Vader). That said I'm equally willing to conceed that it may just be that they were the films I grew up loving and that my opinions above are just rationalization.