'Viva Las Vegas' is not a good film. It is however a great musical, and a very entertaining film. This entertainment value should be the only reason to see this. Granted, there is no other reason to watch any Elvis movie, with the possible exception of 'King Creole'. Alongside the magnificent and early-fire film 'Jailhouse Rock' you won't find a more entertaining film starring the King.
Clearly, that has nothing to do with the screenplay, by Sally Benson, which best line would have to be Ann-Margret's entrance 'My car whistles' and Elvis' reply 'Can't blame it'. If that is the 'wittiest' line of your movie, you've got a problem. There's no originality, no wit, no character development (or even creation, to start with), no story.
THE SONGS: One of the most consistent soundtracks for ELvis films, mostly hits, next to none misses. Highlight is the title song which hasn't lost one ounce of its excitement in the last 40 years. The duet 'The Lady Loves Me' with Ann-Margret isn't far behind. Elvis didn't duet often, and this is his best one. Actually the lyrics of the song seem far more clever and funny than the whole screenplay. Ann-Margret's a good singer, underrated certainly, and her solo numbers 'Appreciation' suffers from bad composing, not from bad singing. Elvis is on high form on the rocker 'C'mom everybody'.
THE DANCING: The University of Nevada bit is the centerpiece here as far as dancing goes and it's a joy to watch. Good choreography and Elvis is seen with the excitement and pleasure he had in the fifties, and seemingly lost. Ann-Margret arguably out-dances and up-stages him here, which shouldn't be seen as disrespectful to him but merely as a compliment to her.
THE ACTING: Without fleshed out characters written, you can't have them acted. Elvis was not a bad actor, and even if he did appear unnatural and stiff in other films, he seems quite energetic and talented here. Ann-Margret's a better actress, natural and talented.
THE DIRECTION: Sidney knows how to film musicals, he was one of the best of the genre, so no complaints here at all. I like the race at the end which may even be called 'exciting' at times.
THE CO-STAR: Without any doubt this is the reason for the film's success, both in entertainment and financially. Ann-Margret in her fourth movie is, quite simply put, great. She can sing, dance, act, and I guess there's no explanation needed on how she looks. In her prime, and she's in it here, she was Hollywood's most attractive actress - face and body-wise, but with enough talent to move way beyond starlet-status. Her costumes are great (take special notice of her black-tights-red-sweater wear in the Nevada university number). There's a typical amount of bad 60s makeup (in the otherwise great 'What'd I say' routine) and hairdo, but that's not too much of a problem.
THE CHEMISTRY: Another point that sets Viva Las Vegas apart from, for example, Speedway with Nancy Sinatra, is the on-screen chemistry between Elvis and Ann-M. Love affair or not, these are simply two attractive people liking each other and making the romance in the film really believable. They both seem like they had one hell of a good time.
THE STORY: What story? Race car driver wants to win both the race and the girl. He succeeds in both. Wow.
TO SUM IT UP: Of all Elvis movies of the 1960s this is the best. The soundtrack is unbeatable, the King himself never again seemed to have so much fun, and in Ann-Margret there's not only his most attractive but also best co-star.