The Washington power structure, which prides itself on having seen everything at one time or another, never saw anything quite like Saudi King Fahd's dinner for 600-plus of his best American friends last night.

There they were, titans of America's military-industrial complex, wandering around the posh new J.W. Marriott Hotel wondering not when they were going to eat but where.

As confusion goes, this one was a doozy. Visualize hundreds of guests in couture gowns and black tie without their table assignments right up to a few minutes before the dinner was scheduled to begin. Not that anyone was going hungry. The food at the reception was fit for a royal court.

The Saudis, who reportedly spent $500 per person on the dinner, tried to sort out the confusion by passing around 67 typewritten sheets, each representing a table. That left guests looking for their names by thumbing through the lists with one hand while holding their banana frappe's and smoothies in the other.

In the next room, King Fahd and Vice President Bush lined up to shake the 600-plus hands. Suddenly, to everyone's delight (read it relief), a Saudi voice came over a public address system and began reading off assignments for the dinner's 67 tables. In the hubbub, however, some didn't hear their names called.

For instance, the chief executive officers of corporations like Bechtel, General Electric and Lockheed looked lost without their outriders, who usually steer them through life's thornier moments. But they weren't the only ones. Others included a healthy representation of the administration, the Hill, the news media and the diplomatic corps.

"I know my table number," said British Ambassador Sir Oliver Wright with a devil-may-care grin. "But it may not be the same thing."

Inside the grand ballroom, knowing the table number was no guarantee of a seat. Los Angeles Times Washington bureau chief Jack Nelson and his wife, author Barbara Matusow, first were told to go to Table 2, then to Table 32, then back to 2.

"It's a nightmare," said an aide to Saudi Ambassador Prince Bandar bin Sultan, who painstakingly had overseen every detail of the dinner since preparations began on it six weeks ago. "We were waiting for the prince to come and okay the table numbers, but he didn't come when he was supposed to."

When he did, he switched around 80 of the more than 300 invited couples, according to one source. It apparently was a reflection of Bandar's determination to match tablemates to the best advantage. For example, at one table was a leading Midwest arms merchant and a Pentagon officer involved in military procurement.

Despite the table mix-up, guests appeared to be having the time of their lives -- even without the help of alcohol, since the Saudis don't serve it for religious reasons.

"It's about the most plush dinner I've ever attended in Washington," said former representative Paul Findley (R-Ill.). "The only thing to rival it was Jimmy Carter's dinner on the South Lawn for Anwar Sadat and Menachem Begin."

Findley called it "an impressive assembly of people -- almost the entire index of my new book is here tonight."

Findley's book, "They Dare to Speak Out -- People and Institutions Confront Israel's Lobby," is being published by Lawrence Hill and Co. of West Point, Conn. "I went to several of the major houses but they said it was too controversial," said Findley, who blames his 1982 defeat in part on his challenge to U.S. policy regarding Israel.

Others in the crowd were Defense Secretary Caspar Weinberger, Secretary of State George Shultz, Attorney General William French Smith, CIA Director William Casey, Joint Chiefs of Staff Chairman Gen. John Vessey, former Senate majority leader Howard Baker, former senator Charles Percy, former Cabinet members Cyrus Vance, George Ball, Elliot Richardson, Philip Klutznick and James Schlesinger, and Time magazine editor in chief Henry Grunwald.

The vice president dined at the king's side. Unlike at most reciprocal dinners, the principals at this one kept their remarks confined to their table. Because there was no champagne, there were no toasts, and Fahd apparently also decided to dispense with after-dinner remarks.

On Bush's other side was Supreme Court Justice Sandra Day O'Connor, who talked throughout the meal to Bush and to Fahd through an interpreter.

Behind them was a 12-by-12-foot rendition of the Saudi royal emblem re-created in hundreds of gold-dipped and white carnations.

Bandar shared a table with Vance and U.S. Ambassador to the Vatican William Wilson. At a nearby table was Sheik Zaki Yamani, the country's oil minister, with U.S. Ambassador to Saudi Arabia Walter Cutler. Rep. Mary Rose Oakar (D-Ohio) and Rep. Nick Joe Rahall II (D-W. Va.), both of Lebanese extraction, were also in the crowd.

Serving the king was the hotel's director of catering, Egyptian-born Mohammed Ihsan. Earlier in the day, he had tried to make sure there would be no sour notes by leading his 135 waiters through a careful rehearsal three hours before the dinner. It involved split-second synchronization that required waiters to step forward simultaneously to each of the 67 tables, bow from the waist and start the service.

"I think that the grace and harmony of movement and timing of service are far better than flaming desserts," said Ihsan. The rehearsal seemed to pay off.

Certainly nobody missed anything so mundane as flaming desserts. Pastry chef Rudi Weider had spent a week creating 85 chocolate boxes and making 2,000 chocolate truffles, 1,500 chocolate-dipped strawberries, 1,000 almond clusters and 2,500 pieces of baklava, not to mention strawberry mousse and several hundred Saudi royal seals in marzipan.

Bandar forbade the use of trays to carry the food from kitchen to ballroom, so in addition to two waiters assigned each table, there was a third who acted as go-between. "The prince didn't want a convention atmosphere," said Tuni Kyi, director of food and beverage.

Bandar also specified that the two cornets of smoked salmon served each of the king's guests be completely filled with caviar. Executive chef John Hughes personally divided the 62 pounds of beluga caviar into two-ounce servings.

"It's the best," said Hughes. And at today's prices of about $236 a pound, who could dispute it?

Hughes oversaw preparation of the menu, which Bandar selected from four that were presented him in trial tastings several weeks ago. At the alcohol-free reception, where the pie ce de re'sistance was an ice-sculpture ship beneath a custom-made green and gold sail, were 2,000 oysters on the half shell and 2,000 fancy clams. Later at dinner, after the caviar course, there was saute'ed medallions of veal topped with sauce morel, potatoes be'arnaise masquerading as almond-covered pears, and a variety of vegetables, including tomato skins shaped into roses.

The grand ballroom's 67 tables were covered with green cotton and overlaid with gold cloths. Besides echoing the official Saudi colors, they complemented colors of the food in the six-course meal. Taped Arabic music played throughout the night.

"People always associate Saudi Arabia with extravagance but they forget that we started from scratch," said one Saudi official. "What happened to us in 20 years took you more than 100."