For every sun-filled winter vacation you plan, there is some envious soul ready to pour boiling suntain oil on it.

"I have bad news for you," one such naysayer announced upon hearing of my Caribbean escape program. "St. Maarten is dull, dull, dull."

If only he could have been at Juliana Airport that Friday, as "dull" St. Maarten greeted its sun-starved visitors with no less than television cameras, a raucous steel band and buckets of chilled Moet et Chandon.

Surely that was not S.O.P. on St. Maarten, a lush, 35-mile-long island high in the Leeward chain? An official-looking type, posted strategically near the champagne, looked momentarily blank. Then he flashed an easy smile and replied in flawless French.

"On inaugure L' avion," he explained, as if every airport christened every new flight accordingly.

Unfortunately, the celebration of the new nonstop service from Miami to St. Maarter was not for those who descended from the two planes that had landed minutes apart at the tiny airport. Instead, we were whisked through a perfunctory customs check.

Just as quickly, the sound of the steel band was replaced by the shouts of bellowing tour group organizers. Dead ringers for camp counselors in their "ELKIN REP" T-shirts, they were accounting for their travelers, crossing each name off on their clipboards. For the majority of the travelers on those two planes - as is largely the case on St. Maarten - had come to the island via bargain-rate package trips. And in the bargain, as it were, they had taken on a kind of summer-camp-for-grow-nups demeanor; exchange their polyesters for cutoff shorts and they'd have divided into teams for volleyball.

That left those of us who had found our way to St. Maarten on our own - on our own. But not for long. Soon we were piling into buses (themselves reminiscent of summer camp transport) and chugging up the hill to the Mullet Bay Beach Hotel.

"I've heard Mullet Bay is, uh, rather spread out," the naysayer had warned in casual, if gross, understatement. The combination of hotel, condominium and recreational facilities that makes up Mullet stretches across 170 acres. Mullet has an 18-hole golf course, 18 tennis courts, two large fresh-water swimming pools, a half-mile-long private beach and boating on Simpson Bay lagoon. It also has five restaurants (including one disco-hamburger-quiche type nightspot); a large, characterless convention center; a bank and grocery store; an assortment of boutiques abounding in overpriced resort wear/souvenirs; and, of course, the casino, with its gaming tables and wall-to-wall slot machines.

In one week in December, an average of 900 guests per day were registered at Mullet, and still the complex was not filled to capacity. To its credit, the resort did not seem as crowded as it obviously was. Tennis courts went shamefully unused; beach chairs and chaises were never lacking; the lone jogger on the golf course encountered little interference from cart-bound golfers.

To that extent, Mullet's disparate nature works in its favor. Guests stay not in some mammoth central facility, but in compact, two-story complexes that offer bare-bones double room ($48 in season) or more spacious suites. The latter, at $72, in season, are really one-bedroom apartments, with a large living room, tiled balcony and kitchen.

But like some vast tropical subdivision, these units stretch across the whole of Mullet's 170 acres. And since many of the guests neglected to pack hiking boots, having apparently abandoned their walking skills with their days at summer camp, they were left dependent on rental cars or the resort's "courtesy" bus service.

Though these open-air vans do traverse the property at almost any hour, they are perhaps misnamed. At Mullet, "courtesy" is generally less in evidence than "bureaucracy." Room phones come equipped with a lengthy list of Centrex Phone numbers for different services. But staffers at these desks have discovered the virtues of the hold button (as in "Activities Desk. Please hold. CLICK!"). Better to march down to the desk itself than face such suspended telephone animation.

The bureaucracy is nowhere more apparent than on the beach, where the keeper of the towels works a 9-5 day and logs each towel as assiduously as registered mail.Forget to turn in a towel by closing time and your name goes straight to the head office. If that doesn't strike the fear of God in you, maybe the $10 fee for each unreturned towel will.

Luckily the beach at Mullet is not all red tape. Bartenders at the two thatched-roof watering spots have dreamed up a lovely, if lethal, "Island Sunset," consisting of token amounts of fruit juice and shots from almost every bottle on the shelf. And at least one beachboy tried his hand at friendliness toward a UCLA T-shirt-clad sunbather, crooning "Ookia, ookia, what a lovely name."

The mistake was innocent enough. Many smart sunbathers combat the strong Caribbean sun by donning T-shirts, often emblanonid with their first names. Others were spotted in one of the island's hottest items, the navy blue "SM" T-shirts sold at the resort's Windward Islanders shop.

But shopping in St. Maarten is not all T-shirts and woven placemats. Phillipsburg, capital city of the Dutch side, is a gold mine for duty-free shopping. From a point as distant as Mullet Bay, the 20 minute cab ride to Philipsburg will cost around $5. A little investigating turns up a journey bus service, offering the same ride for 40 cents.

Though Philipsburg has experienced a kind of tropical urban sprawl in recent year, the town has not lost its village atmosphere. The two main shopping streets, Front and Back Streets, are barely two cars wide and are dirt-paved in, some spots; one afternoon, a pig grazed insouciantly in the middle of Back Street.

In the European tradition, the stores in Philipsburg close for two hours at mid-day, at which point tourists abandon their duty-free shopping to flock to the multitude of restaurants. One spot, the West Indian Tavern, modestly claims to make the finest pina colada in the Caribbean. (Maybe so, if you like your pina colads thin and supersweet.) The open-air Tavern is almost too West Indian to be true; huge rattan chairs and tables, with Humphrey Bogart fans twirling overhead. The regulars seem steeped in Caribbean intrigue, deep in conversation over bloody marys or glued to all-night backgammon tables. Closer in on Front Street, the more pedestrian Cafe Nosh caters to New Yorkers who can't go a week without their egg creams and bagels.

Many of Philipsburg's eateries seem subdued - dull, even - by day, but change character by night. L'Escargot, for example, is your basic country French spot for lunch. At night, the quail with raisin is served to the sound of disco records spun by "Byron, the San Francisco disc jockey." L'Escargot encourages dancing by offering free tango lessons.

The serious gourmet, however, will soon head for the French Side. The reward is a feast for the eyes as well as the stomach, since the French Side faily exudes charm.

Marigot, for example, the French capital, seems like a transplanted Mediterranean town. White-washed houses climb hills luck with blooming bougenvillea, while in town proper, traditional blue and white French street signs mark the roads. The harbor's small size may work against it economically - Philipsbur'g larger, deeper port attracts the big tourist ships - but it gives a price less feeling of accessibility. Indeed, visitors seemed as eager to photograph the produce and fish market set up along the water as any other Marigot sight.

Like the entire French Side, Marigot is less developed, and hence less commercial, than its Dutch counterpart. Though well-stocked with French imports, many of Marigot's shops seem geared as much to residents as to tourist, and the midday closing creates less of a rush on restaurants.

The restaurants - ah, the restaurants! The balcony of L'Aventure perches directly over the harbor, affording a marvelous, dreamlike view. The food is perhaps less marvelous, though the pleasant French house wine helps one overlook a lot of mistakes. Chez Lolotte concentrates mainly on creole cooking, some of St. Maarten's more exotic food. Up the road, nearer Grand Case, Le Fish Pot offers succulent daily seafood specials. Many of the locals seem to head for the neighborhood boulangerie.

Surely the star attraction on the French Side (discounting, for the moment, the nude beach, accessible only by hiking through a field of nettles) may also be the star attraction of the entire island. La Samanna occupies its very own peninsula with a kind of splendid isolationism. With its white-washed villa-like atmosphere the resort calls itself "Moorish Mediterranean," and practices what it calls "decided nonchalance."

For this you pay - plenty. A "superior twin" on the European plan costs $137.50. For a three-bedroom villa you will drop $488.40 a day. Even the little ones pay at La Samanna, where a crib in the room costs $22 a day.

Meals and drinks at the poolside bar a priced accordingly. But presumably the ambience justifies the cost for some people since the resort stays full all year. Beautiful People (or at least Famous People) abound at La Samanna: There was the guest who complained about the piped-in soft rock at the poolside bar.Come on, he demanded of the waiter, Neil Sedaka in a Caribbean paradise? The waiter said nothing, but calmly cast his eyes toward the mosaic-tiled pool, where Neil Sedaka floated peacefully.

A visit to La Samanna makes it hard to go home to Mullet Bay, which suddenly seems larger and more crowded than ever. Where on earth did all these millions of people come form? How can they content themselves with staring glassy-eyed at slot machines all night long? Why do their strident voices, forever in search of the Coppertone, compete so with the gentle sound of the surf? Can this really be their idea of a week's respite from reality?

No matter. Issues of existentialism have little relevance when one is tornbetween an Island Sunset and sunset on the island.