I’m not going to disappoint the LOTR fans:
Faramir, post ROTK. Who wouldn’t want to get their hands on Eowyn? 
King Elessar Telcontar, post ROTK: Arwen. 'Nuff said!
Mystique from the X-men universe. I would get my arse down to LA and spend the week shapeshifting into incredibly hot men and having sex with other incredibly hot men.
Job done.
I will bet all the money in my IRA against all the nickels in your piggy bank that June insists on making love with the lights off, while wearing a flannel nightgown with a very small hole in the groin. Also that she spends the entire time staring at the ceiling and thinking of England.
Well, the Mid-west.
Indiana Jones
Or perhaps Dirk Diggler in the first half of Boogie Nights.
Aragorn, obviously, which only approves that he was a Fool of a Took.
So you’re voluntarily jumping into a FoaT? 
I think Aragorn’s a major mistake, actually. If anybody’s gonna see through the illusion of the QLA, it’s an elf–even a half-elf. You’re less likely to find yourself getting some Arwen nookie than you are to find yourself with her knife at your throat and some 'splaining to do.
Also, even post Ringwar, Aragorn was a busy fellow, with lots of wars to fight. Even if you have his memories and physical abilities, you’re still likely to lack his personality, and that’s a major part of being a badass.
The way I was thinking when I wrote the OP was that you would have to jump into the character’s life during a given storyline already chronicled. But as I neglected to specify that, and nobody seems to be operating under that thesis, screw it.
The beauty of the fictional universe I picked it that no one has incurable STDs so a couple round of penicillin once I’m back and everything is all cured up.
I was going to do a :rolleyes:, but then I remembered that you wanted Charlie Harper. The fact that he’s even alive supports your statement. But we’ll need you to memorize the manufacturing protocols for the HIV vaccine while you’re there.
How about Tom the Dancing Bug’s God-Man? Although his total omnipotence is somewhat ambiguous, as he seems to have random limits to his omnipotence depending on the gag. My second choice: the devil from “I of Newton”.
I would jump into Willow Rosenberg right before a certain VERY BAD THING happens. Then I would yell “Duck!”. Then I would enjoy a lovely week of magic, hanging out with the scoobie gang, and… well… other stuff.
Eh, I like the books, and I like the characters. Depending on the period in the books’ history that the leap occurred, jet-setting around and enjoying ambiguous-time-period wealthy life could be fun.
They wouldn’t be my first choices, though. I still think Magneto would be the most fun. I’ve always harbored a secret desire to be able to lift idiot drivers’ cars up and deposit them gently on nearby roofs.
But that’s not enough. Tara looks at you and wonders why, and doesn’t duck in time. She still dies. You meanwhile have interfered with the most powerful witch in North America, who will probably blame you for her sweetie’s death and who is more than capable of hunting you down across realities.
Well, I don’t just jump in 2 seconds ahead of time, for goodness sake. And if she doesn’t duck, I cast some spell or other, having all the capabilities of a super-powerful witch.
I want to be one of the lesser known characters in the Harry Potterverse. One of the Patil twins perhaps. Maybe Susan Bones. Someone who gets all the joy and wonder of having magic at their fingertips but without being the direct target of Voldemort.
Hank Moody.
Really, can there be a better answer? Take a week in the TARDIS and get around. Hell, with his brain and memories just spending a week staring at the wall would be an adventure.
James T. Kirk
To boldly boink bodacious Betelguesian babes until the recall notice is sent.
James Bond - cool gadgets, lots of action, fast cars and always gets the good looking girl at the end
I’d pop into Major Nelson, of I* Dream of Jeannie*. Jeannie will be getting quite the surprise when I come home from the base.
Plus, Jeannie can bend all kinds of rules, so this is going to be a LOT longer than a week.
Do Cartoon characters count? Because if so, it’s a tough call between Stan Smith (American Dad!) and Dr. Byron Orpheus (The Venture Bros.)
Also, are we guaranteed a week in which the character is actually doing something? I mean, Indiana Jones would be awesome for a week where he was out treasure-hunting, but otherwise you’d just be spending a week as a University Professor.
Thursday Next. The metafictional aspects of the books would instantly be increased a hundredfold.