In Los Angeles, where getting into the act isn't an intrusion but a career, the White House is thinking about adding a dinner to mollify all the Reagan friends clamoring to meet Queen Elizabeth II on her state visit early next year.

The Reagans' State Dinner for Elizabeth and Prince Philip is scheduled in San Francisco's DeYoung Museum. When it became apparent there weren't going to be enough seats to go around for everyone who wanted to come, White House aides started thinking about adding another dinner -- this one a nonstate affair in Los Angeles.

There's still a little problem of where to hold it, which says something about the state of state affairs in Hollywood West. So one possibility White House advance teams have been looking into is taking over a Hollywood sound stage, which is something the queen wants to visit anyway. Otherwise, arrangements for her coastline cruise aboard the royal yacht Britannia, are proceeding smartly.

Last week the British ambassador, Sir Oliver Wright, looked over the scene, including Silicon Valley. The queen has let it be known that stretch of electronics firms just north of San Jose is high on her "must see" list. "Can't you imagine showing San Jose to the queen of England?" moaned one administration insider.

Also on the royal itinerary is a luncheon at the Reagans' Rancho del Cielo and, of course, a horseback ride through the sagebrush into the sunset. Unlike last June at Windsor Castle, where Reagan and his extended White House family were the queen's house guests, Elizabeth and Philip will bunk aboard Britannia anchored in Santa Barbara Bay.

The Reagan administration pulled out all the stops in arranging the state visit this week of Pakistan's President Mohammad Zia-Ul-Haq. Tonight at the White House he'll get Henry Kissinger, the Aga Khan, Zsa Zsa Gabor, Kirk Douglas, Freddie Brisson and Alan Pakula, to name but a few among the 130 on the guest list for his State Dinner. Waiting in the wings here and elsewhere starting tomorrow will be a full complement of government VIPs as well as Alexander Haig Jr., Zbigniew Brzezinski, Richard Nixon, Armand Hammer, Walter Wriston, Houston Mayor Kathryn J. Whitmire, Pakistan's honorary consul Joanne Herring and San Francisco Mayor Dianne Feinstein.

Rep. Millicent Fenwick (R-N.J.), who also has heard the rumors that she'll be named ambassador to Italy, came back from Rome after her post-election vacation saying there's "no news" on Italy.

"I saw the Rabbs the other day and they're as happy as everything. There was no suggestion of his leaving," said Fenwick, who is fluent in Italian, as well as French, and pretty good at Spanish.

Even so, with speculation mounting that U.S. Ambassador to Italy Maxwell Rabb may be coming home permanently next year, prospects are growing dimmer that he and his wife Ruth ever will live in a style to which they would like to accustom Villa Taverna, the U.S. embassy residence in Rome.

The sixth-century villa, whose deficiencies Ruth Rabb first pointed out to wealthy New Yorker Iris Rossi more than a year ago, still is in need of a facelift and what Rossi once described as "little statuary ashtrays, some extra chairs, a silver tea set, new upholstery on the dining room chairs, damasks for the walls, exterior paint." But since setting up the Villa Taverna Foundation to reburbish it, Iris Rossi and her husband Raymond have gotten momentarily sidetracked.

Last summer when they were visiting Italy (among other reasons, to measure Villa Taverna for some of its new trimmings), another beneficiary, Georgetown University, came to their attention. That was after the Rev. J. Donald Freeze, GU's provost and executive vice president for academic affairs, gave a dinner for them at GU's Villa le Balze in Fiesole outside Florence. The Rossis were so taken by the dozen or so Georgetown students enrolled in the Charles Augustus Strong Center for Study Abroad that they decided to include a fellowship in their foundation fund-raising efforts.

Friday night, 200 of the Rossis' most supportive friends are joining them and Freeze at the first annual Leonardo Award gala at GU's new Intercultural Center Galleria. Award recipients will be Sen. Pete V. Domenici (R-N.M.); Brig. Gen. James L. Dozier, now stationed at Fort Knox; former ambassador to Italy Clare Boothe Luce, and Marvin Howe Green Jr., head of Reeves Communications which, among other productions, does "That's Incredible."

Not that the foundation's namesake -- the Villa Taverna -- is out in the cold for long. Iris Rossi, whose black hair and large eyes sometimes cause her to be mistaken for Elizabeth Taylor ("She introduces me as her younger sister," says Rossi) already is at work on her next fund-raiser. She expects that one to clear $300,000 next March in Las Vegas. Costing $1,000 per ticket, this Roman Holiday comes complete with toga.

"The party of the decade," says Raymond Rossi, the Pizza Hut tycoon who sold out to Pepsi Cola in 1977 and whose Vermont branch of the family made its fortune in granite.

"I always wanted to do something constructive," says Iris Rossi, who directs her foundation from a Georgetown penthouse. "I didn't want to be just a rich man's wife."

There were several budding talents -- one of them a not-often-heard jazz violinist -- making their White House debuts Saturday in a PBS Christmas season show taping that tout Washington can see Dec. 22 on WETA. But the 180 guests, including Vice President George Bush and his wife Barbara, were first to hear and see the All-Star Jazz group including that maybe hottest of all fiddlers -- Itzhak Perlman.

There he was backed up by such established "sidemen" as Chick Corea on the East Room 88; Dizzy Gillespie, blowing his bent horn, and Stan Getz, the old sax smoothie. Playing everybody's favorite, "Summertime," Perlman sawed away to his heart's delight on his worth-the-earth violin.

"I've always been a little jealous of players who have the freedom to improvise," Perlman, the joy of classical music lovers, told the audience.

Also in the act, and the reason everybody was there: Jon Faddis, a bent-trumpet protege of Dizzy's, and Diane Schuur, a blind blues singer from Seattle whom Getz discovered three years ago at the Monterey Jazz Festival.

President Ronald Reagan wasn't back yet from Latin America but First Lady Nancy Reagan carried on by welcoming the guests as part of the ongoing Young Artists in Performance at the White House series. Then Perlman, the host this year, took over as emcee, parodying a political position you sometimes hear in these parts:

"I talked to my wife and children, and I'm not running. Actually," said Perlman, who is crippled by polio, "I haven't run in years."

If touch football is a Kennedy tradition, so, for Ethel Kennedy, is Thanksgiving at Georgetown University Hospital. At John Coleman's star-studded Ritz-Carlton Sunday brunch saluting show-biz types here for the Kennedy Center Honors, Kennedy responded to the usual question about how Thanksgiving went. "The usual," she said, "the usual touch football and the usual trip to the hospital." Time out came on the playing fields of Hickory Hill when a K-tribe casualty headed for the hospital with a hurt finger. "I haven't missed a Thanksgiving there in 12 years," Ethel Kennedy said.