It had been an exhausting trip, with stops in London, Paris, Geneva, and Paris a second time, so Sen. William L. Scott (R-Va.) seemed pleased that the opening ceremonies of the Interparliamentary Union spring meeting here were brief.

After the pageantry of the opening session, as most of the other 600-plus delegates from 75 nations headed for work sessions being held through Friday, Scott returned to the luxurious Hotel Ritz along with his wife and most of the other women who are accompanying their husbands on this all-expense-paid trip.

Scott, Rep. Joseph L. Fisher (D-Va.), three other U.S. senators, nine other congressmen and a number of congressional employes are representing the United States at teh IPU meeting here. They and their wives are flying on U.S. government jets, staying at the best hotels and eating fancy meals, with most of the bills being paid by the U.S. government.

When the Air Force jet that has skipped around Europe on the way to this meeting with Scott and the 49 other Americans touched down at Lisbon Airport Monday night, it marked the 38th country that Scott has visited at taxpayers' expense since he was elected to the House in 1966.

If Scott is the current king of Capitol Hill junketeers - he has plenty of rivals for the title - the IPU conference now under way is the grandfather of junkets. Senators and congressmen and their wifes have been coming to these meetings since 1889.

What began as an annual affair is now twice a year, and the schedule makers have a knack for picking the right place at the right time.

Portugal is now in spring bloom, and flowers are competing for space with drying clothes on the balconies of the apartment buildings that line the narrow streets of this sunny capital city.

Although the IPU conference did not start until yesterday, the tour began last Wednesday at the beginning of what Congress likes to call its Easter work recess.

The chartered Air Force jet ook off from Andrews Air Force Base for London. The group moved on to Paris on Friday, where most of them remained until coming here Monday.

The Scotts, however, were part of a smaller group that flew to Geneva Monday for six hours.

Scott met with Paul Warneke, the chief U.S. negotiator on the SALT talks, while his wife toured the city by bus.

In between the work sessions here this week, the delegation will be feted at a presidential palace reception by Gen. Ramalho Eanes, and can pick from a variety of events, including a trip to the shrine of Fatima, casino gambling on the shores of the Atlantic, bullfighting and a special performance of the National Ballet.

This is the third time in his 5 1/2 years in the Senate that Scott has been a delegate to IPU meetings.

He previously attended meetings in Australia and Romania.

And after he bumped into a German delegate yesterday afternoon, Scott, whowill retire when his term expires in January, said he started thinking about squeezing one more IPU meeting into his travel log, in Bonn later this year.

The German delegate told Scott he recognized him because they had sat at the same table at a previous IPU meeting.

"He told me he'd take me for a trip on the Rhine" said Scott, who said he didn't remember the German's name.

For a politician, Scott doesn't have much of a memory for names.

He said, for example, that during the London stopover the party "met with the British foreign minister, I don't remember his name. Some call him secretary of state. A young man, about 42. He seemed to be very knowledgeable."

Scott said his talk with Foreign Minister David Owen "covered a wide variety of subjects."

Scott did better when he tried to recall the name of the U.S. ambassador to Portugal, with whom he had breakfast yesterday. He reached in his pocket and pulled out an agenda prepared by the United States Information Agency that listed the name of Ambassador Richard Bloomfield, newly arrived here from Ecuador.

Although Scott didn't say why he skipped the opening committee meetings, he expressed disappointment that he didn't get the assignment he had hoped for.

As a member of the Senate Armed Service Committee, Scott said "it seemed reasonable" for him to be on the IPU committee on political questions, international security and disarmament, but two other senators along on the trip "wanted that committee and they outranked me."

Instead, Scott wound up on the committee on educational, scientific cultural and environmental questions. It will debate the question of how to solve the increasing illiteracy as a threat to world development.

"I've got some literature in my briefcase on illiterates in the world," Scott said. "We need to find a way to educate the masses."

Asked if he thought the leisurely schedule of the conference, along with the side trips to England, France and Switzerland, might be interpreted by some people as a junket, Scott shot back to the reporter: "Is it a junket for you?"

Scott insisted that the government "gets value for this."

The IPU differs from the United Nations and other international forums in that its delegates speak their personal views, rather than those of their countries, Scott explained.

"THe State Department is helpful" in preparing position papers on the subjects to be discussed, Scott said, "but we can disagree. We're free to say and so as we please."

Scott said that "you could say the U.N. isn't needed. You could say that of any international gathering. Is it a junket when the president or the secretary of state visits from place to place?"

Scott pointed out that many of the delegates at the meeting represent poor, emerging nations. "We're one of the wealthiest nations in the world. If it's a junket for us, it's a junket for them, too."

The four senators and 10 congressmen all brought their wives, as did three congressional staff employes.

"The wives don't pay as a matter of protocol," Scott said. He said he and his wife get "room and board and transportation. That's it. No per diem."

Scott said that if they spend money on their own "it comes out of my pocket." He patted his trouser belt, with a secret compartment for carrying traveler's checks and added, "If I go home with money left over, I can cash these in."

The senator said members of the delegation "can submit vouchers for other expenses, for which they would be reimbursed, but "I don't intend to do that."

Scott said his conservative political philosophy extends to his personal habits. "I might take a drink of wine, but that's about it. That holds my expenses down."

The official party here is headed by Sen. John Sparkman (D-Ala.), chairman of the Senate Foreign Relations Committee. Others in the Senate delegation are Robert T. Stafford (R-Vt.) Abraham Ribicoff (D-Conn.) and Scott.

The House delegation is led by Rep. Richardson Preyer (D-N.C.) and includes Rep. Robert McClory (R-III.), Edward J. Derwinski (R-III.), Fisher, M. Caldwell Butler (R-Va.), Lionel Van Deerlin (D-Calif.), J.J. (Jake Pickle (D-Tex.) E. (Kika) de la Garza (D-Tex.), Lawrence Coughlin (R-Pa.) and David Bowen (D-Miss.)