Robert Redford and Nick Nolte go for “A Walk in the Woods” in Ken Kwapis’ broad, bland adaptation of Bill Bryson’s 1998 tome. Like that mildly amusing travel-memoir-cum-elongated-humor-column, there’s light diversion but little substance in this tale of two grumpy old men making a predictable hash of their effort to hike the Appalachian Trail. The appeal of the cast names and the equally venerable scenic vistas should lure older audiences, though whether they’ll get out to theaters or wait for home-format delivery is an open question.

With his grandkids coming of age and peers dying off, Bill (Redford) here worries he’s losing his mojo with little time to spare; ergo his very random decision to hike the 2,200-mile trail, a determined whim that his English wife, Cathy (Emma Thompson), considers foolish and dangerous at his age. She insists that at least he not travel alone. No one else is tempted to sign on, however, until out of the blue, Bill gets a call from fellow Iowa native Stephen Katz (Nolte), who invites himself along. Stephen hasn’t been heard from for decades, not since the duo had a youthful falling out while traveling in Europe.

Bill hasn’t been much of a hiker for a good 30 years or so. But he’s in Olympian shape compared with the careening wreck of Stephen, who tumbles off the plane in New Hampshire looking like a diabetic hobo. He’s overweight, and his status as a recovering alcoholic is a bit questionable. (There’s a whisky bottle in his rucksack.) Nonetheless, the duo soldier on to Georgia to commence their wheezing trek in the spring, intending to make it all the way to Maine before winter.

As they slog north, they have encounters with a cartoonishly obnoxious younger backpacker (Kristen Schaal), take a few pratfalls, scare off some bears, and occasionally stop to recoup at the nearest hotel. At one of the latter, Bill flirts with an attractive innkeeper (Mary Steenburgen) while chubby chaser Katz gets in hot water pursuing a local lass who turns out to have a very jealous husband.

Casting the 78-year-old Redford lends this quest a fear-of-mortality undercurrent duly spelled out in Rick Kerb and Bill Holderman’s competent but uninspired screenplay. His character keeps insisting, “I’m not writing a book” — but it was obvious from reading Bryson’s original (penned when he was just in his 40s) that the trip was little more than an excuse to drum up some funny anecdotes for just that purpose. The material remains essentially slight, buoyed along, but given precious little surprise, by its star thesps.

Given some of the author’s zingers, Redford (who originally planned to co-star with his iconic screen buddy, the late Paul Newman) gets to flash more crusty humor than he has in some time. Taking on his most prominent role in a few years, Nolte is entertaining but could hardly be more typecast — he’s been playing variations on this shambling rascal since “Down and Out in Beverly Hills” 29 years ago. While his always phlegmy delivery is good for some laughs, it’s so raspy now that at times he’s downright unintelligible. Supporting players are given little to do, even less of it interesting.

Sitcom veteran Kwapis has seldom been an inspired bigscreen helmer —his best such effort may well be “The Sisterhood of the Traveling Pants” — and this workmanlike entertainment, comfortably paced and bereft of notable atmosphere, nuance or twists, does nothing to change that assessment. It’s pleasant enough cinematic comfort food, but even so, you may be hungry again soon afterward. The pro package is inevitably highlighted by some splendid aerial location shots in John Bailey’s widescreen location lensing. Not adding a whole lot of flavor is a sometimes overamped soundtrack dominated by unmemorable rootsy rock-folk songs by indie band Lord Huron.