Excitement Rises Like Brigadoon on Potomac : Ceremony: Every four years, the jaded capital of politics gets gee-whiz emotional over the parades, the dinners, the galas, the tourist dollars.

You can’t get away from it unless you leave town. If you are anywhere near the Washington-Baltimore metropolitan area, you will become infected. An air of expectation is everywhere.

Take the street vendors, on virtually every corner, who have happily switched from hawking slow-moving Redskins items to briskly selling T-shirts and buttons bearing the inaugural seal or the ebullient faces of Bill and Hillary.

“It’s going to be good,” said Stafford Lowry, who has spent the last 36 years selling souvenirs on the streets of Washington and put two of his five children through college on his earnings. “You can tell.”

Or take the cookie lady behind the counter at Mrs. Fields, who can barely contain her anticipation. “Well, honey, are you ready for Wednesday?” she asked with a broad smile as she handed over a pound of the store’s finest chewy fudge. “ I can’t wait.”

This city is in a good mood. It is preparing to inaugurate a new President, and its spirits are showing.

“The entire atmosphere is charged with energy,” said Bernetta Hayes, a local Chamber of Commerce official. “You can feel it in the streets. People are grinning.”

New lights have been strung along the Memorial Bridge over the Potomac River in preparation for President-elect Bill Clinton’s walk from the Lincoln Memorial to Arlington National Cemetery for Sunday night’s bell-ringing ceremony. The inaugural platform has been erected on Capitol Hill, ready for the presidential swearing-in. The bleachers are up along the Pennsylvania Avenue parade route, and the huge enclosed, weather-proof reviewing stand in front of the White House awaits its new occupants.

Even Mother Nature promises to cooperate, with cool, partly sunny weather, with highs in the 30s, predicted for Wednesday, and no threat of rain or snow.

“We expect the largest crowd in 205 years of inaugural history,” said Sen. Wendell H. Ford (D-Ky.), chairman of the Joint Inaugural Committee. “There are no tickets left. Demand was unprecedented.”

Tens of thousands of out-of-towners will flood into the city by Monday, and they will be greeted at the rail station and airports by 200 volunteers passing out maps and subway and bus information. They also will hand out souvenir bags of T-shirts and buttons, and brochures on city restaurants and night life.

The visitors are expected to pour at least $50 million into the local economy over the four-day inaugural period. Caterers are furiously busy, and, not surprisingly, there is hardly a hotel room to be found anywhere.

“We are totally booked,” said Karren Walsh of the Hay-Adams, the small, elegant hotel across Lafayette Park from the White House where the Clintons stayed during their first post-election visit to Washington.

The Hay-Adams is planning to present its guests with a gift of a special edition, numbered inaugural plate as a memento, “which is something we hope they will treasure,” Walsh said.

And for caterers, the quadrennial event brings a special boom during an ordinarily slow time.

“January is normally dead, but, all of a sudden, every four years, it’s party time,” said Jay Treadwell, president of Movable Feast. “If you looked at it like an EKG, it would start out flat on Monday--like a dead person’s--then zip into life for three days, just like someone had jolted your heart--and then go flat again on Thursday.”

The florists are as busy as the caterers, with an even greater challenge: turning this mostly marble and granite city into bloom in the middle of winter.

At least 100 floral designers from around the country have been brought to Washington by the Society of American Florists to produce flowering decorations--with red and white the principal colors--for the numerous inaugural dinners, balls and galas.

Thousands of flowers began arriving Friday at the society’s special 20,000-square-foot headquarters in Springfield, Va., outside Washington.

“We’re very fortunate to be able to tap into such a formidable network of florists, wholesalers, growers and suppliers,” said Jim Leider, president of the society.

The inaugural will be a virtual smorgasbord of events--balls, concerts and meals, both official and unofficial, elegant and informal, expensive and free.

Besides the highly publicized festivities--the bell-ringing ceremony, a Barbra Streisand concert, the salutes to children and youth--there will be countless other places to eat, drink, be merry--and even be thoughtful.

The National Archives, for example, will host an inaugural book fair Tuesday and Thursday, with talks by authors on the presidency--or, as in the case of former Democratic Sen. George S. McGovern--even former candidates for it.

And, in addition to the regional inaugural balls that occur every four years regardless of who is elected, there will be inaugural balls like none Washington has ever seen: a gay and lesbian inaugural ball and an environmental ball, which features invitations on recycled paper and will offer organically grown food.

“America’s Reunion on the Mall,” sponsored by the official inaugural committee, will be a free outdoor festival with hundreds of entertainers, artisans and food vendors from around the nation. The Chamber of Commerce expects at least 100,000 people to show up before it ends Monday.

The event “is a celebration of everything that makes our country great--especially diversity,” said Ed Emerson, its executive producer.

So, with the celebration unavoidably under way, some people have taken the you-can’t-get-away-from-it-unless-you-leave-town notion literally, choosing to do just that.

President Bush’s daughter, Dorothy Koch, who lives and works here, has gone off to Florida with her family to avoid seeing Bill Clinton take over the White House. That’s understandable.

Puzzling, however, is the case of one Democrat--a congressional aide--who left Saturday for Vermont and a week of skiing. She says the work on Capitol Hill is quiet--the last slow period Congress will have for a while.

“I don’t like parties anyway, particularly if I have to pay to go to them,” she said, adding: “I’m a good Democrat. I’m just antisocial.”