Surely there are as many good reasons for traveling as there are travelers: To see exotic places and cultures (satisfying curiosity); to study the art treasures of Europe (educational); to marvel at America's scenic beauty (inspirational); to climb a high mountain range (meeting a challenge); or to visit friends and family back home (obligatory).

All worthy goals, certainly, but next time how about a vacation just for the fun of it?

A treat. A celebration. A reward for just being you. A hassle-free fling with free time to be lazy without guilt. A lark, with no other motive except to enjoy.

It can refresh perspective, brighten the spirit, regenerate creative processes and put a bounce in your step.

Of course, every traveler has a different idea of what constitutes fun, but most would look for a relaxing getaway that promises a good share of these characteristics:

Pampering of the body and palate; plenty of unstructured time; the excitement of something or some place new; sightseeing only when you feel like it; convivial company, if desired; minimal goals, demands and responsibilities; and pleasant accommodations and attractive surroundings.

Some people might want to add "at a bargain price" to the list, but once in awhile it's fun to splurge, to spend more than you usually do to get the room with the best view or dine (just this once) in the city's finest and most expensive restaurant. Pleasant memories reward for a lifetime.

If this all sounds terribly self-indulgent, well, it is. But you, your family and your work may all benefit if you return relaxed, smiling and full of renewed zest.

A trip for the fun of it can be an escape to an island resort; a balloon flight in Europe; a weekend playing mystery games; a night in a Japanese-style hotel; or a marvelously unusual trip across the Alps.

An example of each of these holidays is described below, beginning with the transalpine journey. It's very expensive, but it sounds like great fun. Convince yourself you earned it.

Across the Alps by mail: a whimsical adventure with cheery comfort. You board a coach drawn by a team of four horses for a 20-day ride through the Alps from Munich via Innsbruck, Austria, and the Brenner Pass to Verona and Venice in northern Italy.

The path -- mostly over secondary or even private roads -- follows the footsteps of Johann Wolfgang von Goethe, the 19th-century German poet and dramatist who made a famous two-year trip through Italy. Sit back and relive the days when travelers had a chance to really see the countryside.

The re-created itinerary is leisurely, too, assures Lindblad Travel, which is offering about 10 departures from April through October of 1986. The coach will cover between 20 and 40 miles a day, with plenty of stops to stretch legs and photograph mountain views.

Accommodations are in inns, a number of them historic, including the same hostelry in Bolzano where Goethe slept on his journey. The ride is limited to 10 people, and there is seating inside and out (depending on the weather).

From the mountains, the coach descends through Italian vineyards and orchards to Verona, where passengers will change to motorcoach for the final leg of the journey to Venice and a three-night stay.

The land price, including all meals, is $3,995 per person (double occupancy). Air fare is extra.

For a copy of the brochure, "Goethe's Italian Journey by Coach-and-Four Across the Alps," contact: Lindblad Travel Inc., P.O. Box 912, One Sylvan Road North, Westport, Conn. 06881, (203) 226-8531 or (800) 243-5657.

*The game of sleuths and suspects. The setting is classic Agatha Christie: Well-mannered guests are gathered at a country estate, seemingly for a pleasant holiday weekend. But someone in the party has murder in mind, and guests, one after another, are dispatched with astonishing frequency.

Who is the culprit? The host, the butler, your affable dinner partner who looks like she would never harm a soul?

Everyone is suspect; everyone remains a possible victim. And everyone can be the amateur detective who puts an end to the skullduggery so those who are still breathing can leave for home on time.

In the past couple of years, murder-mystery weekends have become extremely popular, taking place in country inns, city hotels and aboard trains and even cruise ships. It's a chance for mystery readers (or fans of late-night movies) to make themselves a character in their favorite fiction.

Blyth & Company of Toronto, one of the largest mystery weekend operators, has scheduled a dozen programs across the United States this fall and winter, including five at East Coast inns.

Typically, 50 to 60 paying participants gather Friday night at the inn for a wine and cheese reception before dinner. In their midst are a half-dozen professional actors, who may identify themselves as guests or part of the hotel staff. Suddenly, someone is murdered; the "inspector" is summoned and the game is on.

Some guests look on the mystery as the evening's entertainment -- a form of theater, says Blyth spokesman Charles Adison, and they spend their days enjoying the inn's recreational facilities or touring the neighborhood. But a certain percentage, the real mystery buffs, are very serious sleuths, spending the whole weekend trying to solve the crime.

Each mystery plot is original and often complex, and each utilizes the particular layout of the inn and its surroundings. You have to be a good detective, says Adison, to find out who did it.

A rule of the mystery game is that everyone must share clues, and anything found is brought to Saturday night's dinner for observation. Most of the action takes place at Friday and Saturday dinners, when the entire group is gathered in a private dining room at the inn.

The solution comes at Sunday brunch, when guests can point an accusing finger (if they think they know the culprit), and the "inspector" makes an arrest. Successful detectives take home a small mystery-related prize.

On the East Coast, Blyth has scheduled mystery weekends at the following inns (price per person, double occupancy, includes lodging and meals except Saturday lunch):

Mountain View House, Whitefield, N.H., Sept. 20-22, $255; Inn at Starlight Lake, Starlight, Pa., Oct. 25-27, $245; Montauk Inn and Yacht Club, Montauk, N.Y., Nov. 8-10, $265; Sterling Inn, South Sterling, Pa., Nov. 22-24, $265; and the Williamsburg Hospitality House, Williamsburg, Va., Jan. 24-26, $265.

For information: Blyth & Company, 2808 Winthrop Rd., Lincoln, Neb. 68502, (402) 488-4192 or (800) 228-7712.

*The pleasures of a Japanese tub. It's a tub for two, so you'll want to take a companion; but you don't have to fly to Tokyo. The Japanese-owned New Otani Hotel and Garden in downtown Los Angeles has set aside a handful of special suites for what it calls "a Japanese experience."

This is a one-night, once-in-a-lifetime whim you indulge yourself, because it's fun to try something new and because it's fun to watch the delight on your companion's face when you open the door to your suite and step into Traditional Japan.

Or at least a semblance of it. The parlor of the two-room suite is more traditional American, with western-style furnishings for western comfort. Behind a sliding shoji screen, however, is the sleeping area, an elevated tatami room with woven reed mats on the floor. The bed is a futon, a thick, soft cushion unrolled on the mats.

You remove your shoes before entering the tatami, and each guest is provided a pair of slippers. To complete the evening's dress, guests will also find yukatas, the ankle-length, wrap-around Japanese kimonos with billowing sleeves that can double as pockets.

The "Japanese Experience," a one-night, all-inclusive package for two, begins with welcoming sips of sake, the rice wine, taken in your suite or just outside on the small, private terrace that overlooks a half-acre Japanese rock garden.

Next, perhaps, is a visit to the hotel's Sanwa Health Club for a half-hour shiatsu massage by Japanese-trained masseuses. The shiatsu is described as "a combination of fingertip pressure therapy and Northern European techniques." The massage is part of the package.

Each of the suites offers a traditional Japanese-style tub, with a modern Jacuzzi. Guests properly soap and rinse in an antechamber before stepping into the chest-deep, steaming water for a before-dinner soak.

A Japanese dinner is prepared at your table in the hotel's elegant A Thousand Cranes restaurant, which opens onto the garden and its waterfall. And next morning, you have a choice of a traditional Japanese breakfast (fish, rice, soup) or an American one. On Sunday, there's "A Touch of Japan Brunch" for late sleepers.

The price for two, including tax, tips and valet parking, is $329 a night (Sunday through Thursday) and $349 on Friday and Saturday. A lot of money, sure, but a fine way to celebrate a special birthday or anniversary.

For information: The New Otani Hotel & Garden, 120 South Los Angeles St., Los Angeles, Calif. 90012, (213) 629-1200.

*Ballooning Over Salzburg. Among the pleasures of ballooning are the sweeping views, and Salzburg, Austria, the birthplace of Mozart, offers some of Europe's most magnificent scenery. The most famous scenery, too, since the city and the countryside are where "The Sound of Music" was filmed.

To see it all, the Bombard Society of McLean, a balloon-tour organizer, plans an annual fall series of flights over the lake-dotted foothills of the Alps around Salzburg.

The six-day program calls for daily 90-minute flights, mostly at tree-top level, followed by an elegant, leisurely champagne picnic lunch. Ground-level sightseeing fills the afternoons.

Guests stay for three nights in a deluxe downtown hotel and three nights in a lakeside inn nearby. This is a trip for early risers, since the ride to the launch site leaves the hotel about 7:30 a.m. Everyone helps prepare the balloons for the 90-minute flight.

Each group is limited to 12 persons, six to a balloon, and the launching sites are changed daily.

The path of the balloon depends on the day's wind currents, but pilots try to keep the balloons low for maximum sightseeing. "We want people to be able to see the people below," says the society's Lynda Everman.

The price for the program is $3,850 per person (double occupancy), including lodging, all meals, ballooning and sightseeing. Air fare is extra. Departures are weekly this season from Tuesday through Oct. 8.

Among the firm's other European ballooning programs: five days in Burgundy or a half-week or full week in the Loire Valley of France; a week in Switzerland, divided between Bern and Lucerne; and a week in the Tuscan hills of Italy around the hilltop city of Siena.

For more information: The Bombard Society, 6727 Curran St., McLean, Va. 22101, (703) 448-9407 or (800) 862-8539.

*Romantic Caribbean escapes, for couples only: more fun for two, which can be the most fun.

Couples-only beach resorts are a recent trend in the Caribbean resorts, and one of the newest is Couples, a small resort on the lovely green island of St. Lucia. Once claimed by the British, English-speaking St. Lucia is now an independent country of gorgeous mountains and large banana plantations.

At Couples, they take the name seriously. No singles, no children. Only the two of you (and, to be sure, 85 other couples), accommodated in clusters of low-rise bungalows on six acres just north of the capital of Castries. (There's another Couples and other similar resorts on the island of Jamaica.)

An added attraction for many visitors is the all-inclusive price policy. You know up front how much a week-long vacation will cost, since everything is included in the price: lodging, meals, hotel/airport transfers, recreational facilities and instruction, sightseeing, wine at meals, even drinks at the bar. Tips and taxes, too.

You don't realize how relaxing this can be, says a spokeswoman, until after the first drink or two at the bar, when the bartender doesn't ring up a tab and walks away from a tip.

Once or twice a week, the resort welcomes guests aboard a two-masted sailing vessel for a cruise down the coast (no extra charge). One stop is in an isolated bay where you can, literally, walk the plank for a cooling dip in the clear, quiet sea. Afterwards, vans carry sightseers first to a bubbling volcano and then on to a high mountain resort for lunch with a grand view.

Athletic couples can try sailing, windsurfing, water skiing, snorkeling, scuba diving, bicycling, horseback riding and tennis, all available at the resort. Contemplative souls can doze under a beach umbrella or alongside the swimming pool.

The price per couple from Sept. 6 to Dec. 19 is $1,470 for seven nights; after that, it climbs to $1,890 until April 7 (except Jan. 4 to 16, which is $1,750.) Air fare is extra. Gogo Tours of Fairfax City (703-359-3530) offers a round-trip air fare on Pan Am from Washington National via New York City for $350 per person weekdays and $385 on Saturdays and Sundays.

In addition to three full meals a day, guests are treated to hors d'oeuvres at 5 p.m. and a midnight snack in the piano bar -- which, claims the resort, only closes "when the last couple goes to bed."

For more information: Mars Leisure Corp., 211 Essex St., Suite 306, Hackensack, N.J. 07601.