So most of us agree that his turn was unfulfilling and full of holes. My question is: how would you have done it?
I would have dressed Padme (sp?) in a skimpy leather suit complete with whips and chains. Throwm my best Jedi mind trick on her and suggest she go make Anikin her bitch. (Thus turning him to the dark side)
I’m thinking my version would have gotten MUCH better reviews. 
Before the movie came out my prediction went something like this. Slightly predicted by Anakins actions against the Sand People.
So you’re the Emperor and you’ve got yourself a war going on. Anakin’s got some sort of leadership position. Since you are secretly behind both sides you can manipulate things to put him in some a position where he has to commit war crimes and other things against the Jedi way in order to save the day. You may have to guide his mentality into committing such acts before hand. During these series of acts convince him of his herohood and how he had to do those things in order to win, that he is essential to the safety of those at home, particularly Padme. Maybe begin suggestions that the Jedi are afraid or jealous of him. Anticipate the Jedi recalling him and build it up in his mind as a humilitating experience.
Hopefully he’ll refuse to turn over his command forcing a Jedi response. This was where I envisioned the battle beween Obi Wan and Anakin. Or he’s taken back to Coruscant where you can continue to work on him as he is confined.
Tell him about the great dental plan, of course. 
In all seriousness, there is no wiser source on how to manipulate Anakin than the great Jedi Master, Yoda himself, in his words to the young Skywalker:
Anakin is scared. You need to play off of that fear, and make him angry at that which would realize his fears. Make him hate what would realize his fears, and sic him on it. And when I say “it” I mean “the Jedi.”
See, Lucas had the right idea, but he needed to make it not so much a targetless fear of Padme dying. You need a scapegoat. You say to Anakin, “Look! The Jedi don’t want you to learn what could save her! They’re The Man, and they’re keeping you down! Are you gonna let The Man keep you down! FIGHT THE POWER!”
Wrangle a White House overnight visit for him, including hot cocoa with Karl Rove. That should just about do it.
Pay off his student loans.
Pam Grier. Ain’t no going back from that.
Fresh-baked cookies. Who can resist those?
<nitpick>Darth Vader, by definition, is already turned to the dark side.</nitpick>
Anakin Skywalker was a whiner that would have ended up turning to the dark side just because everyone didn’t think he was as important as he thought he was. To turn him into your dark apprentice, give him a cookie, some milk, and listen to him rant and sympathize a little.
My only problem with the movie is that Anakin turned too quickly. There should have been another scene or two showing Anakin at odds with the council. The basic premise was actually pretty good. Anakin felt unappreciated, and the Jedi were still treating him like a kid even though he’d proven his abilities. That’s exactly the sort of person who tends to become a spy or a double-agent.
As for using Padme as a hook, well, they do say that the road to Hell is paved with good intentions.
First of all, you tell him that it’s the *Cool Side * of the Force. Remind him that all the Sith get to wear black and never have to do any of that totaly bogus crap that the Jedi have to do, like clean their room or be back before 11PM.
Donuts.
< I haven’t seen the latest installment…6 or 3 or whatever it is , but Darth turns to the dark side? whooo knew?>
/i keed.
I agree, but I think it should have been shown in a different way - Anakin deciding that no matter what the council thinks, he’ll stay good, and do his best - and then getting totally rebuffed by the council anyway. It’s not just his fear of them, but their fear of him, that kept them at odds.
Other than that, I like **Fern Forest’s ** idea.
They should have played up the Jedi councels rule against Jedi’s marrying. So their could be more of a schism between Anakin and the Council. Plus emperor manipulating events so Anakin is involved in more and more bloody conflicts.
Sell Anakin on some minor plastic surgery, then botch the job. Have him awaken in a dimly lit room as you peel the bandages off. Hand him a hand mirror.
Upon seeing his new face, he’ll bellow out an anguished “Nooooooooooooooo!”, break the mirror on a side table, then throw on a cloak and rush out of the room, pausing only to snarl at some passersby in the alleyway.
He’ll be irreversibly evil at this point.