When Warner LeRoy went shopping for something to wear recently, he found just the right thing at his favorite costumer. It was red and glittery and sequined and had that LeRoy look, which is to say a cross between Diamond Jim Brady and a Rose Bowl float -- but the woman behind the counter wouldn't sell it to him. He begged. He pleaded. He kvetched. He threw his weight around, all 270 pounds of it. Finally, the woman said, "I can't sell it. It's the elephant's cape for the circus." LeRoy had them make him one just like it.

That was maybe the second biggest thing LeRoy -- the impresario behind New York's Maxwell's Plum and Tavern on the Green -- ever got into. The first is Potomac, his multitier, 1,000-seat "grand cafe'" opening to the public on the Georgetown waterfront July 31. It took five years to build at a cost of $12 million -- and LeRoy says he'll give it two weeks.

"It's like a show. If this place doesn't do well in the first two weeks, why should it do well after that? My investors will not be happy with that," he laughs, but "my creation is done. That's the fun. I would not be prepared to keep it going if it didn't work."

LeRoy's basic idea, a moderately priced cafe' catering to the masses, is not new. Even his carnival-like atmosphere has been done before. It's the scale of this project -- 40,000 square feet, requiring seven miles of electrical wiring -- that has Washingtonians wondering if it will fly. Even the workers aren't sure. On a recent visit, one of them had posted a sign outside the electrical room, snaking with wires and switches: "Shuttle Challenger Control Room."

"It's a huge restaurant," says LeRoy, who thinks it may be the most expensive ever built. "Luckily I've never had a failure."

He is wearing a $10,000 shiny gold lame' jacket festooned with fat red, purple and orange flowers designed by his friend Yves Saint Laurent. His pale blue eyes beam behind thick glasses and his brown hair is matted with perspiration as he moves like an ocean liner through the waves of workers buzzing over his latest production. Electricians on scaffolding are fitting the 20-foot ceiling with swirls of tiny light bulbs, over which 800,000 handmade colored jewels will be placed.sw,-2 sk,2 ld,10 It is Steven Spielberg's version of the Sistine Chapel.

LeRoy designed it himself. He also designed the specially dyed carpet of 49 colors, the tablecloths, the china, the white beech chairs and the peach beveled mirrors that will line the walls. He wants the whole place to sparkle and shimmer, with 24 imported crystal chandeliers and wall sconces and silver candelabra all bouncing off the luminous night light of the river, and you get the feeling that one more tiny light bulb will blow the city's collective fuse.

Overhead, a brass model of the 1935 Southern Pacific Super Chief will circle the restaurant, chugging along in an acrylic tube.

Warner LeRoy, 51, is the first one to tell you he doesn't know when to say when. Why have one terrace when there's room for five? Why have one fully grown London plane tree when you can afford seven? Why settle for a few whiskey barrels sprouting impatiens when 8,000 evergreen and blooming plants are at your disposal?

"It's my art," he says. "I can't move people if I'm neutral."

He steps out on the concrete terrace. It is hot and dusty and the gardeners and bricklayers have taken a lunch break. LeRoy frowns at the towering, newly transplanted trees, held by wire and metal stakes. The leaves are shriveled and brown.

"They're in shock," he says, laughing again.

It has been said that Warner LeRoy, accent on the second syllable, is not a restaurateur at all. He's a set designer.

"That's how Warner sees it," says Potomac's general manager, Carl Bruggemeier. "As a 20-year movie."

Bruggemeier is sitting in his cramped, windowless office off the restaurant's balcony, going over the opening-night menu. He knows that after LeRoy opens the show, he has to keep it running. He seems jittery. He's thinking of quitting smoking. Now is not the time.

Not when you have 600 Surprise Chocolate Meltdowns to worry about.

That's what they're serving for dessert. Bruggemeier had an exact miniatures of the Capitol dome cast in metal by a Buffalo firm. From that, he had his staff make hundreds of plastic molds, 4 inches across by 5 inches high, which will be dipped in chocolate. Once unmolded, the chocolate Capitol domes will be filled with espresso ice cream and fresh raspberries. Over it, a boiling hot vanilla sauce will be poured, melting the dome into the ice cream and raspberries.

Unless it doesn't work. "It does work," Bruggemeier says.

Besides the spectacular parade of courses, introduced by models in "sexy Cher-type costumes" hoisted by male body builders, the opening-night ceremony will include a jazz band, people on sway poles, water-skiers, scullers, a Baccarat champagne fountain and a man opening bottles of bubbly with a saber.

"I love what I do," LeRoy says, sitting on the wooden boardwalk overlooking the Potomac. "I know some people are going to say it's vulgar, that it's overdone, but I understand that. That's what theater is."

He is a jovial man whose waistline, as well as his reputation, precedes him -- living proof that eating well is the best revenge. He loves children, balloons, clowns. He has, friends say, the heart and mind of a child. He's seen "Casablanca" 50 times, and if they ever make The Warner LeRoy Story, he'd want Sydney Greenstreet to play him.

In sequins, of course.

"He's the Mike Todd of the restaurant business," gushes Elaine Kaufman, proprietor of the celebrity-packed Manhattan cafe' that bears her name. "He's fabulous."

Other New York competitors have nothing but praise for LeRoy's style.

"He is the last showman in the restaurant business," says Vincent Sardi, owner of Sardis. "He breaks all the rules and does it beautifully."

*"He's a genius," says Mike O'Neal, proprietor of the Ginger Man. "He's a Hollywood person transported to the East Coast. He comes out of that crazy California scene."

Whether he knows anything about good food is another matter.

Skeptics say LeRoy spends too much time on the frenzied ambiance of his restaurants and not enough time on the fare. Maxwell's Plum and Tavern on the Green have not enjoyed enthusiastic reception from the critics.

According to Marian Burros, New York Times food columnist and former restaurant critic, "no self-respecting eater" would be caught in either. In the recent Zagat Survey of New York restaurants, one critic called Tavern on the Green "a culinary catastrophe." Offered another: "Took home a doggie bag. The dog refused it."

LeRoy takes bad reviews better than most. New York Times restaurant critic Bryan Miller says he was surprised when he got a call from the restaurateur after an unfavorable review of Tavern on the Green. "He thanked me for the comments," Miller says. "He said he agreed with some of them. Usually, these people are ready to split me with a meat cleaver. He's a straight shooter, and sincere."

"He wants desperately for the food to be wonderful," says author and New York Magazine restaurant critic Gael Greene. "It doesn't have to be wonderful. The fairy tale atmosphere," she says, is more than enough.

Well, almost enough. It still helps to put booze in the Bloodies.

When New York Magazine did a survey several years ago, rating the amount of alcohol in the Bloody Marys served in bars and restaurants, Maxwell's Plum twice scored a zero. There was no vodka in the drinks. LeRoy showed up at the editor's office, demanding to know why he was being singled out. After a friendly chat, he went back to the restaurants and discovered for himself what New York already knew. LeRoy sent a case of Smirnoff silver vodka to the magazine. Maxwell's now serves the vodka in a shot glass at the table.

LeRoy was the first person in Manhattan to spend $100,000 a year on a chef, and he was widely hailed for bringing in a husband-and-wife team from L.A.'s trendy Spago to jazz up Maxwell's menu last year. But he wasn't prepared to take risks with Potomac. Instead, he hired dependable Michel Bourdeaux, former executive chef at Maxwell's.

It has been suggested in restaurant circles that Potomac will have to sell 1,000 meals a day just to break even, and that unless he gets tour buses back to back ("What's wrong with that?" he asks; "the White House is full of tourists"), he may have trouble filling the space. Commuters tend to dine in the suburbs once they arrive home, and other Washingtonians are reluctant to fight the growing Mardi gras Georgetown scene. And on one recent afternoon, the low-flying planes approaching National Airport made conversation on the terrace all but impossible.

LeRoy admits it's not the sort of place people are likely to hang out. "I want everyone in Washington to come one day a year," he says.

As an outsider, he admits, maybe he's naive about what the natives want.

But naivete' has helped him before.

"When I opened Maxwell's Plum on First Avenue, they said, 'No one will go to First Avenue. It's a catastrophe.' Then when I went into Central Park, they said, 'Are you crazy? People will get killed.' I've had this so many times in my life. There are always people who are going to say it won't work. I think if it's good it will work."

"People will come to look," predicts Burros, a Washingtonian. "But I don't think they'll come back." At least one local restaurant critic agrees: "I think it's going to be the greatest white elephant that Washington has ever seen."

*"I hope not," LeRoy says. Ultimately, he claims, it doesn't matter whether people come. "It's really like a work of art. Does a painter think who is going to look at his painting?"

But he does care, he insists, about the food. Why else would he fly in lamb from Colorado, artichokes from California, lobster from Maine, Cavaillon melon from France, white truffles from Italy, chocolate from Belgium and much, much more.

"When I worked in the theater," he says, "I was Garson Kanin's assistant. When I first started, he was a brilliant director. He said to me if you wanted to do things that were good and exciting, you had to go out on a limb. You had to just keep going out, and eventually you were going to fall off. And that was good. Because that meant you really pushed yourself.

"I guess that's what I'm doing. I just keep trying to push myself further and further and further. Someday I'm going to fall off."

As the great-nephew of the legendary Jack Warner and the son of director Mervyn LeRoy -- whose films included "Little Caesar," "Five Star Final," "Little Women," "Mister Roberts" and "Gypsy" -- Warner LeRoy knows something about fantasy.

The grandson and namesake of Harry Warner, a founder of Warner Bros., LeRoy was born in Hollywood. When he was 4, he visited the set of "The Wizard of Oz," which his father was producing. He skipped down the Yellow Brick Road, only to run smack into a wall. The road was only 20 feet long; the rest was a painting.

"That's when I knew there was a line between fantasy and reality," he says. Sometimes that line was blurred, though -- he did get to keep Toto as a pet.

He loved to visit the back lots of the studios. "In those days," he recalls, "everything was made in Hollywood because of the speed of the film and the lights. When my father did 'Waterloo Bridge,' they built the bridge in the back lot. I remember going to London with him years later and him looking at Waterloo Bridge and saying, 'Just like my movie.' " In his father's mind, says LeRoy, it wasn't "that the movie was like the real, but the real was like his movie."

His parents divorced when he was 7. He says he has few memories of his adolescence, except that he was spoiled and that he stuttered. "I can remember waking up one morning when I was 11 and saying I'm not going to do this again. I had thought about it for years. From that moment on, it got better. It didn't go away but by the time I was 18, it was pretty much what it is now." (He says he stutters only under stress.)

* He went to several exclusive prep schools, his favorite being Le Rosey, in Switzerland, where the present Aga Khan was his roommate and where "the worst thing you could do, what you really got in trouble for, was if you didn't put out your shoes at night to be polished."

Growing up in Hollywood, LeRoy says, he was "part of the most exclusive club there is. It was nothing for me to come home and find Albert Einstein" at the house. "Everyone in the world was there." All this was very nice, "but I am not impressed by it." He does point out, with a certain amount of pride, that his father introduced Ronald and Nancy Reagan to each other.

He graduated from Stanford University with a degree in English, and worked in Hollywood as a script reader, film editor, actor and director. From 1956 to 1966, he produced and directed plays in New York, becoming a force in the off-Broadway movement. He left Hollywood, he says, because "I wanted to be my own person. I had so many friends who were under the thumb of their family, and even though my family wasn't like that, I thought it was not for me . . .

LeRoy became obsessed with art (he is a notable collector), with gardening and, finally, with food. In 1966 he opened Maxwell's Plum, which quickly became the state-of-the-art singles bar. Three years later he expanded it and its popularity soared. He constructed a lavish outdoor cafe' there, and helped persuade the city to allow other Manhattan restaurants to construct similar cafe's. In 1976 he opened Tavern on the Green.

He met his second wife, Kay, a former TWA flight attendant from England, the second night Maxwell's was open. They share an 18-room duplex in the Dakota when they're in town.

He is known as a wonderful host, throwing star-studded parties (Cary Grant and Kurt Vonnegut Jr. and "60 Minutes" producer Don Hewitt are his buddies) at the Amagansett, Long Island, home where he summers with Kay and their three children.

Rousing the kids in the morning, he is likely to boom, "Today is going to be a Great Adventure."

Several years ago, the LeRoys took their children to Hollywood to see where Daddy had grown up. They drove to the studios, then toured the exclusive Bel Air streets where LeRoy pointed out the old homes of the stars. "That's where Clark Gable lived . . . That's where Jean Harlow lived . . . "

"My wife is a world class athlete," says LeRoy proudly. "She gets up every morning at 5 a.m. and swims and runs."

What does he do?

"I design the gym."

He also spent $4,000 on a stair-climbing machine. Several years ago, he went on a strict diet, shedding nearly half his weight. But he gained it all back and more.

"I decided I liked him better that way," says Gael Greene. "He needs to be big in order to be special."

Does he have time for lunch? Certainly. He says he'll meet you at the nearby Japanese restaurant in 10 minutes. Ten minutes later, to the second, LeRoy appears, out of breath. He has changed out of his gold lame' jacket and back into his work pants, plaid shirt and Reeboks.

The interior is dark and hushed, with waitresses in kimonos softly padding by.

"Now this is what I'd call a more ordinary restaurant experience," he confides, opening the sparse menu. "Ours is an assault."

LeRoy has had his share of legal hassles and disappointments. Several years ago he filed a $30 million suit against Hardwicke Cos. Inc. -- his former partner in the two New York restaurants and his $100 million safari park in New Jersey, Great Adventure -- for breach of contract after Hardwicke pulled out of several restaurant deals. Hardwicke, in turn, sued LeRoy, accusing him of fraud and racketeering. Hardwicke eventually filed for bankruptcy, LeRoy says, adding that the charges against him were "totally fabricated."

"They thought if they put my name in the paper, it would upset me. They just totally misread me. I told them that anybody who wears the kind of silly suits I do doesn't care what's in the paper."

Hardwicke was originally penciled in as a Potomac investor. When the company pulled out, LeRoy found other financial backing, including the Felds, who own the Ringling Bros. and Barnum & Bailey Circus. Potomac was originally set to open in the fall of 1985, but construction delays forced the opening back. It was also scaled down from 2,000 seats to 1,000 seats, and the six tiers became two.

In 1975 he opened a Maxwell's Plum in San Francisco, but sold it three years ago. It was too far away, he now says. He also sold his interest in Great Adventure, and recently dropped plans to open a restaurant in New York's Bryant Park.

He says he had hoped to design 11 different restaurants for the Smithsonian, but that a tangled web of bureaucracy and misunderstandings got in the way.

Friends say LeRoy has always had more money than he knows what to do with. His worth, he says, is "in the high eight figures" although he doesn't own a black tie and was recently stopped at the door of Maxim's in New York for inappropriate attire before someone recognized him.

He worries sometimes that his outrageous clothes give the wrong impression.

"I think that all the glittery suits and all the flash -- people think that's the real me."

He would love for the president and first lady to visit Potomac, but not on opening night.

What? Miss the model "in Venus costume With Shell Background" carrying a banner announcing the "Mosaic of Salmon and Bass" course? Miss the juggler, the two body builders carrying a live mermaid, the Samba Queen, the replica of an active volcano, the Ziegfeld girls, the fireworks by Zambelli and the one-of-a-kind $10,000 white embroidered jacket from Paris that LeRoy will be sporting?

"The worst thing," he says, would be "if nobody shows up. That certainly can happen . . . "

He takes a bite of sushi, washes it down with Diet Coke.

"I would not consider it a waste. I would consider it a failure, but I wouldn't consider it a waste . . . I'll be somewhat poorer and unhappy and I'll probably never be able to do another one like it, which I'm not sure I want to do."

So if the people come, terrific. "If they don't, I'll go back to my garden. It's gotten totally out of control." Wide grin. "I keep saying to myself, 'How can I charge admission to this?' "