Any way you look at “Sideways,” it’s a winner.

As character study, as an exercise in American ambiance or, simply as an entertaining movie, “Sideways” triumphs.

Director/co-screenwriter Alexander Payne and writing partner Jim Taylor previously gave us “About Schmidt,” “Election” and “Citizen Ruth,” all humorously thought-provoking ventures. “Sideways” is their best collaboration yet.

Miles (Paul Giamatti of “American Splendor” acclaim) and Jack (Thomas Haden Church of “Wings”) are best friends, onetime college roommates who tour California’s wine country one week before Jack’s wedding. Neither will be the same person when he returns.

Miles looks forward to an odyssey of elegant wines. Jack looks forward to as many women as he can handle in his final week of bachelorhood. On their trip, they meet two women who are capable of changing their lives, if the men will allow them.

Through it all, Payne exhibits a rich understanding of human interaction. The dialogue crackles with wit that’s rooted in reality.

Like Payne’s other “road picture,” “About Schmidt,” “Sideways” traffics in locations that seem instantly accessible. And that same accessibility illuminates the characters who live there.