Who needs endless research and planning?Instead, follow Ellen Tien's example, and find your family's next getaway somewhere in the ether—or in a snapshot from a book

It started with a small black-and-white photograph in a Sally Bedell Smith biography of John and Jackie Kennedy. The image was of a man and a woman on a chaise longue, unsmilingly angular and elegant, and altogether pleased by their angular elegance. "Stas and Lee Radziwill at the Half Moon Hotel in Jamaica," read the caption, "shortly before their first visit to the White House in March 1961."

As I sat in our Connecticut weekend house last winter, gazing upon the photo of Jackie's sister, listening to the trees creak in the blowing snow, these words knocked loudly on the door of my id: I want to pose languidly on a lounge chair! I want to wear Oleg Cassini brocade in 80-degree weather! I want to visit the White House! There was only one obvious solution. On the spot, I booked a week at the Half Moon, in Montego Bay, for Easter.

It's a parent's salvation, the Impulse Vacation, the ideal escape route for working mothers like me who haven't the time or the inclination to obsess over wholesome in-flight snacks or dinosaur-shaped luggage tags. Impulse Vacations—not to be confused with Spur-of-the-Moment Vacations ("Honey, let's eat empanadas tonight…in San Miguel") or Instant Vacations (also known as nervous breakdowns)—can be booked weeks, even months, in advance. The impulsive part lies in the precipitate booking, usually set off by a fleck in the ether—a snatch of movie dialogue, an overheard elevator conversation—even a photo in a book.

In short, the true Impulse Vacation is an exercise in immediate future actualization: an idea boards your brain and then swiftly disembarks, clutching a ruff of plane tickets and hotel reservations. Without wasting precious babysitter minutes, you have laid plans that will, necessarily, coincide with your progeny's school vacation.

You are a good mother!

Yes, you are!

Thus confirming my superior parenting skills, I reserved a five-bedroom Royal Villa at Half Moon and recruited two other sterling mothers and their families to join my husband, my nine-year-old son, and me. We packed our Jack Rogers sandals, bright cotton shifts, and a phalanx of Lacoste shirts. How much Jackier could we get?

Easter morning dawned; we dutifully squished into an overstuffed Air Jamaica plane, our knees tucked neatly under our chins. Four crumb-covered hours later, we deplaned, sixties-style, directly onto the tarmac and waited for an hour or so in a long, jagged customs line. It was an unlovely start to our trip. What would Jackie do?Look the other way, of course.

By the time we reached the Half Moon Air port Lounge, though, the morning had turned a promising corner. A bus whisked us to the resort, a rolling oasis of white stucco and hibiscus and the bluest brand of sea, and dropped us off at our garden-view villa. We were greeted by our smiling staff: a butler, a cook, and a housekeeper. After sitting in every chair and admiring the Anglo-tatty décor, we took a dip in our private pool. "Mom," my son whispered urgently (in hindsight, for greater authenticity, I should have instructed him to call me "Maman"). "We have a butler. We have a butler."

And so much more! For the next week, our circle of six adults and five kids had its own brief, shining Camelot-ish moment. We tooled around the 400-acre resort—roughly the size of Monaco—in golf carts, children clinging to the sides like burdocks, shrieking with delight. We lingered over butler-served breakfasts and nodded knowingly as one of the fathers (Harvard '86) used words like accretive and dimensionality. We dined alfresco and laughed appreciatively as another father (Cambridge '83) charmingly regaled us with the finer points of the English-boarding-school social system. Even the kids (led by a pint-size Jackie look-alike, named Vienna) rose to the occasion, entertaining us at night with clever dinner-theater skits about kingdoms lost and luggage found. All this, mind you, even before we had discovered that there was a fully stocked head shop on the premises.

The days tumbled into nights and more days; we swam with dolphins, had daily massages at the excellent spa, capsized a few kayaks, and downed a cataract of the resort's specialty drink, the Dirty Banana. And on the seventh day, we discovered a key commandment of the Impulse Vacation: Keep it short, because the fantasy can be hard to sustain.

Thy children shalt become feral!

Thy staff shalt grow disputatious!

Thy wardrobe shalt loseth its dimensionality!

Perhaps even Jackie herself was sensing the pallid breath of an overstayed stay when, in 1960, she inexplicably penned her last will and testament during a January sojourn in one of the Half Moon cottages. A framed copy of the document hangs in the hotel lobby, alongside portraits of other notable guests like Prince Charles and Spiro Agnew. "I, Jacqueline Bouvier Kennedy, wish to make provision for my daughter, Caroline—that in the event of her parents' death...everything I have should be left to her—money, furniture, jewelry, etc."

Ouch! Everything to Caroline. No wonder Lee isn't smiling in that picture.

Ellen Tien is a columnist for the New York Times' Sunday Styles section and has written for O.

Half Moon

Rose Hall, Montego Bay, Jamaica; 800/626-0592; www.halfmoon.com; doubles from $275, five-bedroom staffed villas from $1,375.