“Last Vegas” could easily be dismissed as the over-the-hill “Hangover,” but a perfect ensemble cast comfortable with their ages and light-hearted material offers a tender, slightly more serious look at odd-ball friendships whilst gallivanting around Sin City.

Expect the expected. The plot is as predictable as they come. We already know the stereotypes, the situations the characters will haphazardly fall into and exactly how they will be resolved. That would generally kill a movie, but Michael Douglas, Robert De Niro, Morgan Freeman and Kevin Kline keep the stale Vegas act from being a cheap matinee performance. Writer Dan Fogelman (“Cars”) infuses some light drama into the comedy and director John Turteltaub (“National Treasure”) gets spritely, genuine performances from the cast, making “Last Vegas” more like wearing a pair of comfortable shoes rather than getting the last remaining bits of soggy chicken at the casino buffet.

Known in their youth as the Flatbush Four, the quartet of Brooklyn friends had the stereotypical golden oldies childhood before growing apart over the years, only keeping in touch via phone to relay their medical problems. But when never-married Billy (Douglas) finally gets engaged to a 30 year-old woman, Archie (Freeman), Sam (Kline) and Paddy (De Niro) all agree to meet in Vegas for a massive send-off. There’s only one problem: Billy and Paddy loathe each other and haven’t spoken in years.

Problems aside, the four go on a Sin City free-for-all, using their age to their advantage: judging a bikini contest, scoring a ridiculous VIP suite at Aria and becoming the most popular kids in town. Of course there are the required old-age jokes that come with the territory, but the fun is watching these guys let loose.

Countering the aging testosterone is the lovely Mary Steenburgen as Diana, a lonely lounge singer who comes between Billy and Paddy. Having once competed to date the female of their group back in their Flatbush days, Billy and Paddy once again square off over Diana, who is either the biggest threat to their friendship or potentially its saving grace. You can guess which way it goes.

Each character is given adequate time to be relevant; each has their own personal story and issues they need to resolved which are just deep enough to make the audience care. This slice of seriousness adds a great deal, keeping “Last Vegas” from becoming trite and maudlin. Also, having fantastic actors helps matters greatly, too.

There is obvious excitement among the cast, which becomes more contagious as the film progresses. Kline and Freeman especially seem to love the change of pace as the comic relief against the bitter and rivaling Douglas and De Niro. Freeman is much more laid back than we are accustomed and is really the highlight of the film.

Completing the cast are Roger Bart as a drag queen, Jerry Ferrara as a frat boy punk and Romany Malco as the boys’ concierge, but the draw is the Flatbush Four.

With the current crop of heavy films in theaters, “Last Vegas” is a crowd-pleasing, light-hearted alternative.

CBS Films. MPAA Rating: PG-13. Running time: 1 hour and 30 minutes.