My Spanish aunt always jokes that if she’s ever reincarnated, she’d like to come back as a rich American’s second wife’s dog. But even though Diane Keaton plays a first wife in Lawrence Kasdan’s “Darling Companion,” her life (and that of her dog) is no less filled with Telluride vacation homes and Mercedes SUVs.

It’s perhaps a testament to Kasdan’s skill as a writer of dialogue that he makes the movie’s one-percenters into sympathetic, interesting characters, even if the script indulges in one of Hollywood’s laziest tropes — the mystical, magical ethnic person who vibrates on a higher plane and gives the constipated white yuppies the advice they need to get through life.

That role is filled here by the talented Israeli actress Aylet Zurer, playing the granddaughter of a Romany mystic and the daughter of a yogi, but we’ll get to her later.

Keaton stars as Beth, a woman we first see nervously teetering on the edge of empty nest–dom. She’s sad that her married daughter and her grandchild live so far away, but at the same time, she’s eager to find a husband for her other daughter, Grace (Elisabeth Moss). Driving along the Colorado freeway, Beth spots a wounded, abandoned dog and takes it to veterinarian Sam (Jay Ali), who immediately has eyes for Grace.

Beth’s never been much of a dog person, but she decides to save the mutt — whom she names Freeway — from the pound, despite the objections of her husband Joseph (Kevin Kline), a supercilious surgeon.

Cut to a year later, when Sam and Beth are getting married at Joseph and Beth’s house up in the Rockies. After most of the guests leave, Sam takes Freeway for a walk in the woods, whereupon the dog sets out after a deer and doesn’t come back. The disappearance of Freeway sends Beth into a tailspin, and the remaining relatives — Joseph’s sister Penny (Dianne Weist), her boyfriend Russell (Richard Jenkins), and Penny’s doctor son Bryan (Mark Duplass) — set out for several days to search for him.

Guiding their way is Carmen (Zurer), caretaker of the Telluride house, who has visions of the missing dog and sends everyone out on cryptic errands involving blue houses and red-headed women. Over the course of the search, Beth and Joseph will confront the strengths and weaknesses of their marriage, while Bryan will learn to appreciate the new man in his mom’s life — not to mention the obvious attractions of Carmen.

So yes, “Darling Companion” falls firmly into what a friend calls the “Pretty White People with Problems” movie, but like the dog at its center, it cozies its way into your lap and stares at you adoringly until you resist its flaws and find yourself won over. The mopey people of privilege and the I-found-a-foundling plot bring to mind my least favorite of Kasdan’s films, “Grand Canyon,” but this time the actors are such fun to watch and much of the dialogue is so great to listen to that they overcame my resistance to the spoiled boomers and their exotic helper.

It’s the one-on-one scenes here where Kasdan’s banter works best, particularly when these urban, urbane characters find themselves adrift in the wilderness. So when Bryan and Russell are on the run from an unhinged, dog-hoarding loner or Beth is trying to pop Joseph’s dislocated shoulder back in place, “Darling Companion” fires on all cylinders.

Keaton and Kline make a great screen couple, and both of them keep their characters from becoming two-dimensional stereotypes. Beth may be high-strung, yes, but she’s a loving and capable woman whose emotions about Freeway running off unleash lots of pent-up resentments about Joseph; he, on the other hand, may occasionally preen like an egotist, but it’s clear that he’s got it in him to be not just a better husband, but a better brother and uncle as well.

This is the kind of grandparents-on-the-go movie that can stealthily thrive throughout the summer months in the small house at the multiplex while superheroes troop in and out of the large auditorium from week to week. If you find yourself hankering for a dose of comic coziness, you could do worse.