'American Idol' stylists took Frank Sinatra night quite literally from a fashion standpoint, duding up the boy contestants in variations on Sinatra’s famous Rat Pack and the suit, while transforming hippie rocker Crystal Bowersox into a nightclub temptress.

Though the judges didn’t go for Crystal’s very controlled version of “Summer Wind,” she blew us away in a curvy lace gown by Jovani dappled with sparkles, featuring a strapless sweetheart neckline and dramatic mermaid hem. (If you want one, it retails for $550).

With dreds upswept in an elegant ‘do, Crystal was the epitome of a torch singer in a classy speakeasy, and she looked downright glam, though she didn’t seem entirely comfortable with the song or the look.

We loved Lee DeWyze’s fashion take on Sinatra. He’s been doing the untucked shirt, tie and jacket thing all season, but last night the jacket was a tux, and his shoes were the perfect foil – Converse sneakers – so modern.

He’s getting better looking with each show, and even hunky mentor Harry Connick, Jr., said, “My wife (former Victoria’s Secret model Jill Goodacre) thinks he’s really cute” adding that Lee was, “just a new and improved version of me.” High praise.

Michael Lynche “looked the part,” and was downright swanky in his three-piece suit, with crisp white shirt and matching pocket square. And the hat, a jazzy banded snap-brim added to the elegance and mid-century cool.

Finally, Aaron Kelly lost the structured jacket and self-consciously rolled up sleeves, replacing them with a regular blue button down shirt (sleeves to his wrists), tie, and gray vest. He looked good but sounded…well, eh. Poor kid.

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Worst vocals of the night to Casey James. But he looked darn good with a charcoal vest topping a raspberry button down shirt. His famous hair swept back into a bun, and thicker beard, he earned his handsome rep, but man, he bombed in the song department.

Randy Jackson changed it up a bit, wearing a banded polo shirt instead of a cardigan, while Ellen has been going softer and more feminine. Last night she tossed a dotted chiffon scarf around her neck and she looked lovely.

At first we thought Kara Dioguardi and Simon Cowell were both flaunting deep cleavage. But then we realized that Kara was wearing a nude tank under her deep v-neck. Not so Simon.

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