The town of Brodick, base camp for visitors to Arran, offers all the amenities expected from a tourist-geared economy: a supermarket for supplies, post office, bakery, and outfitters for hiking or mountain-biking excursions. At first glance, the town underwhelms, especially when the flood of traffic rolls off each ferry. But if you follow the road north or south out of Brodick, you'll encounter Arran's real magic.

The 20-mile-long island divides neatly into two halves, ringed by a 50-mile road and a series of quaint coastal villages, each with unique flavor and charm. Bucket-and-spade-toting families migrate toward sandier beaches in the south near Whiting Bay, Kildonan, and Blackwaterfoot. Here, meadows and forests offer gentle walks ideal for tiny legs, plus plenty of seaside picnic spots. The area is so serene that a Buddhist sanctuary sits offshore on Holy Island, operated by the Tibetan Rokpa Trust. While kids may not dig an overnight meditative stay, they will get a kick from seeing shaven-headed, saffron-robed monks doing their grocery shopping in the small village of Lamlash.

The landscape becomes more rugged in the northern half of the island, creased by a mini mountain range reminiscent of the harder-to-reach Highlands. The hike to the top of Goatfell, about six hours round trip, climaxes with stunning 360-degree views (if you can see through the mist), while lovely heather-mottled glens spill down the hillsides and feed into tranquil, reflective lochs. While the hike isn't extremely demanding, it's probably not a good option for teeny hikers.

Throughout the island, forested swathes shelter excellent single- and doubletrack mountain biking trails perfect for thrill-seeking fat-tire enthusiasts. For a smoother, kid-friendly ride, spend a couple of days circumnavigating the island by road bike, stopping to camp at pitches that grab your fancy. Quiet roads and mostly gentle pitches make the going not too tough, even for younger riders.

For a family like mine, where roughing will have to wait 'till the end of the era of diapers and bottles, Arran includes a full menu of accommodations, running the gamut from hotels and simple B&Bs to rental properties in all shapes and sizes. Minutes after disembarking from the ferry and driving down Brodick's now-bustling Shore Road, we realized we'd scored the mother lode of accommodations with the Kennels Lodge. The conveniently located former hunting lodge on the grounds of Brodick Castle, one of the island's historic centerpieces, would serve as our home for the week.

The site of a fortress in one shape or another since at least the fifth century—when Gaelic invaders hopscotched their way across the Irish Sea to establish the Kingdom of Dalriada, eventually to become modern-day Scotland—Brodick Castle housed the seat of power for the dukes of Hamilton from the 16th to 19th centuries. As such, it has played parts in some darker chapters of Scottish history, including as a strategic prize for warring clan chieftains, Henry VIII's henchmen, and Oliver Cromwell's rampaging Roundheads.

Today civility reigns on the rhododendron-filled grounds, now maintained by the National Trust for Scotland. The Kennels Lodge—no yelping bloodhounds today, just the five bedrooms, dining room, lounge, and full kitchen—shares the castle's vaulted perch overlooking peaceful Brodick Bay. Better yet, the Kennels offers unfettered access to the castle and its 80-acre woodland estate in utter privacy starting at 4:30 p.m., when the gates close to the public. Rent the lodge and this lovely castle gets thrown in as a bonus. And careworn parents will immediately recognize the energy-burning potential of the jungle gym in the front garden, indoor ping-pong table, and the nearby obstacle course.

Arran's accessibility mirrors its charm, particularly appreciated after trudging off an overnight transatlantic flight. And whether you love the beachcombing, challenging hikes, deep-sea fishing, biking, or golf, you won't get shortchanged on those scenic staples of "shortbread-tin" Scotland. Toss on the Kelty baby backpack and hit the Goatfell trailhead, just meters from the Kennels; or pack everyone into the car to find a deserted beach or picnic-perfect swimming hole. You'll very quickly find that this popular island masks plenty of treasures in its rough.