ECONOMICAL SUMMER IDEAS

ONLY an hour or two before catching a train to the airport, I began to realize what I would miss most about Switzerland: not the high mountain meadows, not the morning view from my hotel window across Lake Lugano, not the lovable little Alpine trains.

More than all that I would miss the everyday Swiss conveniences, the little things that the locals take for granted, but that visitors find remarkable, unmatchable, and highly reportable back home.

Right there on the Bahnhofstrasse, Zurich's famous shopping street, I counted a number of the little items that set Switzerland apart. Take the corner mailbox. Each has a sign listing the postal rates for foreign and domestic mail, saving you a visit to the post office or to an overburdened concierge to learn the price of a postcard stamp. And the box has a set of movable numbers that the collector flips to show the time of the next pickup.

Public phones have carefully worded and illustrated dialing directions in four languages - French, German, Italian, and English. Beside the tram stops are boxes dispensing tickets and posted with a push-button, color-coded map giving routes.

Not that the Swiss way is all maps, dials, and buttons; there is a human touch. In the Globus department store, as in all the shops and stores on the Bahnhofstrasse, you don't have to fumble with phrase-book German. When I picked out a packet of pretty Swiss-made envelopes, the Globus saleswoman noted pleasantly in English that I had chosen business envelopes with cellophane windows - not my intention, she intuited.

Everything, thank goodness, is not clockwork perfect in Switzerland, for no traveler wants to move about without challenge or mystery. I never did figure out the schedules of the many little ferry boats that crisscross Lake Lugano in the palmy Ticino region of southern Switzerland. Instead, I hopped off and on randomly like a boy with a free pass at a carnival midway. In fact, I had something even better, a Swiss Holiday Card.

That handy passport-size, plastic-encased document got me all over the lake and all across Switzerland with no questions asked. It can be used on the entire Swiss railway system, on postal buses, and lake steamers, and it gets you on most cograil and aerial tramways at a 25 or 50 percent discount. The Swiss Holiday Card price will not go up in 1983 at the 15- or 30-day rate, and will rise only slightly for four and eight days. With the 15-day second-class card, which costs $93, you spend only $6.20 a day on travel - surely a bargain if you keep moving.

Switzerland may not be a bargain hunter's dream, but the last time I looked, the dollar still bought 2 francs and the Swiss National Tourist Office was promoting all sorts of economical summer ideas. With a colorful booklet called The Swiss Travel Invention, for example, you can plan a trip for any budget and of any length to both Switzerland and Austria, flying Swissair in at least one direction.

What you do is ''invent'' a trip, either in advance or while moving across Switzerland, using Accommodation Vouchers in five different hotel categories (from $15 to $40 a night per person double occupancy, including continental breakfast). If you choose to plan as you go, you inform the desk clerk where you want to stay the following day, and the room will be booked. You get about by train or by rental car at $129 a week and up.

Another important traveler's aid is a plump red booklet called Selling Switzerland '83, available from the Swiss National Tourist Office in New York, Chicago, and San Francisco. There are 112 pages of tips and ideas, perhaps none so intriguing as the special-interest tours: biking around Lake Geneva, glacier skiing from Chamonix to Saas-Fee, a mule safari in the high Alps, and a chocolate-lover's nine-day tour that stops at Lindt & Spruengli, Tobler, Suchard , and Nestle-Cailler, all famous Swiss chocolatiers.

Another way to see Switzerland is to stay put in a chalet or villa and let the tinkle of cowbells lull you to sleep. The Swiss National Tourist Office has a listing of rental agencies; one of the most reliable is Idyll Ltd., PO Box 405 , Media, Pa. 19063.

Swissair provides most of the service to Geneva and Zurich, but Pan Am has also joined the US-Switzerland market, and Capitol - after a brief layoff - promises to come back on April 27 with 10 percent lower fares than Swissair or Pan Am. Even lower are the roundtrip charter rates such as the weekly (Saturday)

Our last impressions of a country are so often those we carry away. So in a way the burden is on the national carrier, and Swissair seems to bear up well. For one thing the trip from downtown Zurich to the airport is inexpensive and effortless, using the airport train that runs every half-hour and takes just 10 or 12 minutes.

In the air, as on the Bahnhofstrasse and all across Switzerland, I found that it was the little things that counted. Head phones, for instance, were handed out free of charge. The hefty lunch - a heaping hors d'oeuvre plate; thin slices of veal; Swiss cheese, holes and all; dessert; and a bottle of mineral water - came with two sets of cutlery. When the stewardess arrived to take away the dishes she carefully wiped off the pull-down tray in front of each passenger. Such is the stuff of Swiss memories.

For more information, contact the Swiss National Tourist Office - in New York at 608 Fifth Avenue, New York, N.Y. 10020; in Chicago at 104 South Michigan Avenue, Chicago, Ill. 60603; in San Francisco at 250 Stockton Street, San Francisco, Calif. 94108.

Another important travel aid is a new instant-reservation system called Dial Switzerland, 800-223-5105, which caters to such special needs as excursions, city sightseeing, rental cars, and festivals.