You can't make a movie musical without at least trying to get Neil Patrick Harris on board. A Broadway veteran—he's been involved with everything from Rent to Cabaret to Sweeney Todd—Harris has even hosted the Tony Awards four times. Combine that with his womanizing prowess as Barney Stinson on How I Met Your Mother and you've got everything we could ask for in a portrayal of the suave and charismatic Sky Masterson. We'd especially love to see him belt out a rousing rendition of what is arguably the musical's most well-known number, "Luck Be a Lady."

Justin Timberlake has loosely explored the fusion of movies and music with last year's Inside Llewyn Davis, a film about New York's folk music scene in 1961. Now that he's dipped his toes, we think he should leap headfirst into an all-out movie musical and play gambling enthusiast Nathan Detroit. Nathan does the most dancing of any of the men in the show, and fortunately Timberlake has the lightness of foot necessary for those dice-rolling dance numbers. Frankly, we're just ready to sit back and watch him do what he does best: croon, spin around on his toes, and hit some high notes. Plus, his album artwork for The 20/20 Experience is evidence enough that the man can rock slicked-back hair, the most essential part of the Guys and Dolls costume.

What's the point of having an incredible voice if you don't share it with the general masses every once and awhile? We think it's high time Emmy Rossum graced the entertainment world with another movie musical. Her Golden Globe-nominated turn as Christine Daae in 2004's The Phantom of the Opera proofs that her soprano voice is well-suited for the role of Sarah Brown. We think she could pull off a reasonably convincing transition from being an overly buttoned-up and respectable missionary to dancing the night away in Cuba and unexpectedly falling for the last man she could ever imagine.

Not only did Amanda Seyfried's role in the film adaptation of Mamma Mia demonstrate that she can carry Miss Adelaide's belting-within-a-reasonable-range nightclub numbers, we know via Lovelace that she has the vampy sensuousness to play up Adelaide's performances at the Hot Box. Seyfried also has that element of sexy innocence down (Karen Smith of Mean Girls in a bunny suit comes to mind). Plus, we know she'd look cute with Timberlake in a movie that isn't In Time—he even interviewed her for our February 2011 issue. Some girls have all the (hypothetical) luck.

Much like Emmy Rossum, we think it's time Jim Sturgess did another musical, and we can't think of a better role for him than the cheerful best pal of Nathan Detroit, Nicely Nicely Johnson. Not only does Jim have the nice guy persona down, he vocally proved himself in 2007's Across the Universe. He's also been writing and performing his own music since he was a teenager, and has even written music for some of his own films such as 2009's Crossing Over. Nicely Nicely, though a supporting character, delivers one of the most famous songs in the musical: the show-stopping "Sit Down, You're Rocking the Boat," which brings the Save-a-Soul Mission members and a slew of gamblers together in a swell of revivalist fervor. Sounds implausible, yes; but with that voice, we suspect Jim can get anyone to do just about anything.

A big presence (of the literal and figurative varieties) and 1940s-era gangster toughness is needed for the role of Big Jule, a gambler from Chicago whose intimidating reputation precedes him. Mark Wahlberg is never short on bluntness or badassness. He would ideally gain a few pounds to put the "big" in "Big Jule," but Wahlberg is no stranger to shifting his weight for a role. He just lost 40 pounds to film The Gambler and when that's done, he'll need to regain that weight anyway, so we vote he just keep going...