Jane Campion
The Director
The position's still wide open, and aside from Schamus, there are no writers in the mix, so we could well see a writer-director on board, and that might be preferable, in order for someone to stamp a particular vision on a text that could need it. A Focus Features budget means we're unlikely to see a bona-fide A-lister.
Our Pick: New Zealand helmer Jane Campion. The director has shown a sure hand with female sexuality in the Oscar-winning "The Piano," and delved into a darker, S&M happy side of sexuality with "In The Cut." That film was poisonously received (in part thanks to a miscast Meg Ryan, who replaced Nicole Kidman), but it's more interesting than its reputation suggests. If Campion can make a film as chaste as "Bright Star" so sexy, than she could certainly bring genuine eroticism to "Fifty Shades Of Grey," and could probably use a studio-endorsed hit at this point; her current project is the BBC miniseries "Top Of The Lake."
Other Choices We Like: The involvement of Schamus makes his regular collaborator Ang Lee a genuine possibility, and we can absolutely see him being a good choice, particularly after the risque "Lust, Caution," one of the biggest-grossing NC-17 releases ever. Sarah Polley's "Take This Waltz" recently explored similar territory in terms of the awakening of female sexuality, and she'd do a spectacular job, but we can't realistically see her being interested. It'd be fascinating to see Paul Verhoeven's take, but we're not sure Focus would trust him with the material. A safer pair of hands would be Ben Lewin, whose sexually-frank "The Sessions" looks to be a major awards player later this year, although that film's considerably warmer.
Other Possibilities: In terms of more studio-friendly names, Steven Soderbergh might be feasible if he wasn't retiring, while Adrian Lyne made his name on this kind of fare, he's hasn't made a film for a decade, but is currently gearing up to return with "Back Roads." From the indie world, Dee Rees, Debra Granik, Lynn Shelton, Julia Leigh, Sofia Coppola or Paul Schrader would all be interesting choices, but probably unlikely ones, while the riskiest, will-never-happen-but-would-be-perfect choice would be French auteur Catherine Breillat. A good compromise would be Philip Kaufman, who's been in this kind of territory before with "Henry & June" and "Quills," and recently made something of a comeback with HBO's "Hemingway & Gellhorn."

Analeigh Tipton
Anastasia Steele
The Role: A virginal 22-year-old university grad who wants to work in publishing, Anastasia (or Ana), covers for her roommate Kate to interview Christian Grey, and finds herself drawn to him, discovering sides of herself she never knew existed. She's described as a "pale, brown-eyed girl" with "eyes too big for her face"
Our Pick: Analeigh Tipton. The former model (who came to fame thanks to "America's Next Top Model" has made an impressive transition to screen acting, first thanks to rom-com "Crazy Stupid Love" and then Whit Stillman's "Damsels In Distress." A good match for the physical description and age, and a talented actress who's unlikely to make the part as much of a pushover as some might. But despite some risque moments in her modeling, and in a recurring role on HBO's "Hung," would she sign off on the nudity required?
Other Choices We Like: Felicity Jones has become a bit of a fan favorite for the part, and we can certainly see why; although she's 28, she looks significantly younger, and could pull off the inherent innocence of the character easily. But again, she might resist a part quite as explicit as this one, especially as she's being offered everything in town these days. Perhaps more open to it, given some of their past work, are Elizabeth Olsen (although she's equally in demand) or "Game Of Thrones" star Emilia Clarke, if the latter wouldn't be too constricted by her HBO obligations to sign on to a trilogy of movies. Jones' "Albatross" co-star Jessica Brown-Findlay might be a possibility, although the actress oozes sexuality, and we wonder if she could pull of the repressed nature of the role early on.
Other Possibilities: Kristen Stewart, inevitably, has been much talked about by fans, while names like Lily Collins, Anna Kendrick and Shailene Woodley have come up too, though most have more wholesome images. Either Teresa  Palmer or Emily Browning feel like good, if very different fits, while British actress Imogen Poots and rising star Bella Heathcote are very plausible as well. Another offbeat suggestion we like: Samantha Barks, who has a plum role in "Les Miserables" that looks to make her a star.

Tom Hiddleston
Christian Grey
The Role: A 28-year-old billionaire from a troubled background, who's used an interest in dominant sexuality and S&M to avoid opening up emotionally to anyone, who picks Anastasia to be his new submissive. He's described as "tall, well dressed" with "copper-colored hair and intense green eyes." For what it's worth, an academic recently released a photo composite of what women had told him they thought the character looked like, and you can see that here. Spoiler: it doesn't resemble Paul Giamatti.
Our Choice: Fast-rising star Tom Hiddleston. At 31, he's as close to the age required, has his star firmly on the rise thanks to "The Avengers" (which let him be brooding and dark), and is a good fit for the character's description. Has displayed his romantic stripes in "The Deep Blue Sea," and pulled off a strong American accent as F. Scott Fitzgerald in "Midnight In Paris." But would the shackles of his Marvel contract, which likely still has several films to go even after "Thor 2", mean he might resist another franchise for now?
Other Choices We Like: Another Brit, Henry Cavill, could be a good fit for the part, but again, he could be tied up with superhero business for the immediate future, unless "Man Of Steel" tanks. Armie Hammer is another one who springs to mind, but is he too old-money to come off as the son of a crack addict? We like the idea of Joel Kinnaman in the part too, who has a certain exoticism, and likely isn't yet too big to take the role. One chocie that might seem unlikely until you think about it: Benedict Cumberbatch, whose fervent female fanbase has a lot of cross over with a target audience, and has a certain dark sexuality to him (see: "Sherlock"). But is he too old at 35?
Other Choices: Fans have brought up the names of Ryan Gosling, Michael Fassbender and Andrew Garfield, but we can't see any of the three, arguably the most sought-after actors around, being willing to do it, and the same likely goes for Channing Tatum.  Alexander Skarsgard is a more plausible choice, while Justin Timberlake could arguably work too if he tones down certain aspects of his personality. Ian Somerhalder is a serious favorite among fans, but we suspect more for the looks than his acting skills...  For a younger take, rising star Sam Claflin ("Snow White & The Huntsman") might be be possible. And for our curveball: porn star James Deen, currently making his straight acting debut in Paul Schrader and Bret Easton Ellis' "The Canyons."