Every holiday season, there’s at least one movie like “Parental Guidance,” an innocuous, inoffensive, forgettable comedy that you could probably take the whole family to, provided everyone has the stamina to endure nearly more than 90 minutes' worth of Billy Crystal.

That’s no mean feat these days, even though Crystal’s Borscht-Belty timing is as crisp as always. One problem is that he’s always trying so hard – there’s always a bead or two of perspiration flying off his gags. The other is that – and there’s no kind way to put it – he no longer looks like himself. Hollywood is a harsh mistress, and understandably, people do all kinds of things to themselves to assuage the unkind effects of time. Crystal, it seems, has gone a bit too far. He’d be funnier if every two seconds you didn’t have to stop yourself and ask, “Who is that again?”

That’s a shame, because the premise of “Parental Guidance” isn’t bad. Crystal plays Artie Decker, a longtime sports announcer who, at the beginning of the picture, is let go from his job as “da voice” of minor-league baseball team the Fresno Grizzlies. His wife, former weathergirl Diane (Bette Midler), is sympathetic and supportive. But when the couple’s daughter, Alice (Marisa Tomei), asks them if they can trek across the country to watch her kids for a few days while she and the hubby get away for a much-needed break, Diane says “yes” before Artie can protest.

Artie feels he doesn’t know his three grandchildren very well, and he finds his daughter’s parenting methods baffling. (The rules, as we later learn, include things like assuring the child, “Your opinion has value” rather than blurting out, sensibly, “That’s a bad idea.”) But Diane thinks the break will do Artie good, and so the two of them arrive in Atlanta with a passel of inappropriate gifts, including Supersoakers, which violate the parental “no guns” policy but clearly delight the kids.

Alice isn’t keen on the idea of leaving her precious striplings – an uptight violin-playing preteen (Bailee Madison), a shy kid with a stutter (Joshua Rush) and a possible future psychopath with an imaginary friend (Kyle Harrison Breitkopf) – in the care of mom and pop, but her husband (played by the almost criminally agreeable Tom Everett Scott) assures her it will be OK. Still, she can’t tear herself away, and the rest of the picture hinges on the business of strengthening the bonds not just between grandparents and grandkids, but between parents and daughter as well.

Along the way there’s an instance of projectile vomiting, and a rush of child hyperactivity instigated by an ice-cream cake decorated with day-glo colors. (One of Alice’s rules for her children is no sugar whatsoever. In one of his funniest lines, Crystal laments, “No Carvel? That’s one of the saddest things I’ve ever heard.”) Director Andy Fickman (“You Again,” “Race to Witch Mountain”) orchestrates these proceedings as well as anybody could. The script is by Lisa Addario and Joe Syracuse, who wrote the 2007 animated feature “Surf’s Up,” and although the dialogue they’ve written for human characters could probably have been delivered just as easily by cartoon ones, they at least try to put a fresh stamp on the family-bonding template.

And the basic concept – the clash between old-fashioned parenting methods, in which not everybody gets a prize, and new modes of child-rearing in which every instance of mediocrity is rewarded – is a potentially sound one. For the most part, the performers are pleasurable to watch: Tomei has rarely given an unappealing performance, and here she at least brings a spark of life to a thankless role. Midler, dressed in an explosion of vibrant pinks and oranges, comes off as larger than life – but Midler is larger than life, and the movie has the good sense to go with it. Only Crystal seems out of place -- he’s trying to be funny, and it’s the “trying” that’s causing the problem. To age gracefully, you’ve got to go with the flow. Crystal is fighting it every step of the way, and the strain shows.

Grade: C-