Late in the afternoons during the week of the Grand Prix of Monaco, the wealthy and worldly and well-connected gather for cocktails in the bar just off the lobby of the ornate Hotel de Paris.

The maitre d' knows the social register and the Riviera "in crowd." And seats people accordingly.

Proximity to the windows that look out on the Casino Turn-one of the many landmarks on the narrow, twisting, hilly Monte circuit, over which the elite drivers of Formula One racing have been practicing since Thursday for Sunday's 37th "Race through the City"-is a measure of status for people as attuned to seating arrangements as diplomats are to protocol.

The Grand Prix of Monaco is, among other things, a grand reunion for both the motorsports crowd and the international jet set that flocks to the idyllic 368-acre principality that tapers, in an architectural mishmash of old world and modern that somehow works out splendidly, from glistening hills down to the true blue waters of the Mediterranean.

The film festival is going on in Cannes. just down the coast, but the Grand Prix marks the real start of the season on the Cote d'Azur.Gradually during the week, crowned heads and the true playboys of the Western world have made their way to the tax haven ruled so agreeably by Prince Rainier and the former Grace Kelly.

From their palace overlooking the harbor, yachts that would seem like ocean liners in most ports seem modest, indeed, compared with neighbours anchored nearby. In the evening, like fireflies, chatter and laughter and the unmistakable sound of popping champagne corks emanate from their bustling cabins.

The Place du Casino is similarly festive at night. Cocktails are followed by a stroll to dinner and a late at Jimmy's, the favored discotheque where invited quests dance chic to chic, or to the gaming tables, which are open to anyone with money.

The men are immaculate in trim-cut designer suits, the women stunning in the most elegant and revealing outfits imaginable. (A British writer, Peter Evans, once described the archetypal Monaco Grand Prix lady as being "slender as a slice of melba toast, and about the same color.") Surely the richest working men in Monaco this week must be the ones who press suits, the poorest those who sell brassieres.

"Don't you feel the intensive flavor of the past in Monte Carlo during the Grand Prix?" the late British driver, Piers Courage, once mused. "It's as if the '20s are being restaged, as if the whole age is being not simply imitated but actually Relived ."

Come Sunday, the vast majority of the crowd of $200,000 will be commoners, racing buffs from all over the continent and a large contingent of Italians who will drive or ride trains over the border, only 10 miles from Monaco, and set up their own camp on blankets on the hillside.

They will wave red, green and white Italian flags, drink Chianti and scream, "Forza, Ferrari" ("Let's go, Ferrari"), urgin on the favored blood-red cars inspired by the venerable factory team of patriarch Enzo Ferrari, and driven this year by Jody Sckeckter (tied in the current world-championship point standings with Jacques Laffite).

But despite considerable democratization, Grand Prix racing remains the silk stocking district of the sports world, and Monaco its penthouse suite.

It is far removed in spirit and ambience - if not in its central themes of speed, advanced automotive design and engineering, mechanical dexterity and the agile skills of drivers who must be considered great athletes - from American stock car ovals or the celebrated goings-on this weekend at the golden brickyard called Indy.

Grand Prix racing, considered the regal epitome of motorsports in Europe, developed from the original city-to-city auto races around the turn of the century. (The first was 732 miles, from Paris to Bordeaux, in 1895, and afterward the winner said earnestly that no one should ever be permitted to match his terrifying average speed of 15 mph again.)

Grand Prix circuits are still road courses. Some are specially constructed for racing but emulate normal streets, such as the Watkins Glen circuit in upstate New York, site of the U.S. Grand Prix-east.In Long Beach, Calif. (the U.S. Grand Prix-West), and Monte Carlo, the races are run over actual city streets.

When the Grand Prix of Monaco started 50 years ago, most of the drivers were aristocrats or idle rich gentlemen, daring and dashing young fellows with cash in their bank vaults, time on their hands and the adventure of blood sport in their veins.

Grand Prix racing retains some of the trappings of that patrician past, and Monaco is the most tangible link. Prince Rainier and Princess Grace receive the winner in the scarlet, canopied royal box as bluehoods applaud from wrought-iron balconies overlooking the circuit.

But times have changed, too, and Formula One racing is now a multi-million-dollar business, replete with more abundant and visibly gaudy sponsorship than any other sport.

The modern generation of Grand Prix drivers has little in common with its aristocratic predecessors, save for exquisite perception, reflexes and concentration, extraordinary control of hand and foot, and an unquenchable thirst for what reigning world chamption Mario Andretti called, in explaining the motivation of the race driver, "The satisfaction of controlling a wild beast that, at any second, could kill you."

Unlike the party-loving drivers of the past, most Grand Prix racers today are sober professionals who never taste champagne until the race is over and the gala victory celebration is in full swing.

Modern racing teams are like little armies plotting strategic attacks on the 16 circuits whose races count toward the cumulative point standings that determine the world championship for drivers and the Formula One Constructors Assocation Cup.

The larger teams number 30 or more members, including a team manager, the field general in overall charge of operations, several designers, two drivers, an assortment of mechanics, pit crews, and support personnel, down to cooks and bottle washers.

They travel together to 15 countries on four continents over a 10-month period, the lower-echelon members of the team frequently living out of custom-made motor homes and trailerss that convert quickly to full-scale garages.

Formula One cars are handcrafted from a lightweight aluminum alloy, and completely disassembled after each pratice and race, their bodies retouched, their engines tinkered with. They weigh only 1,180 pounds, as delicate as they are powerful.

The differences between the cars are largely in the chassis and the aerodynamic design, which at high speeds is critical. In fact, one persistent criticism of contemporary Formula One racing is that it has become less a test of driving than of design skills.

Consider, for instance, that three recent world champions who have switched teams - Emerson Fittipaldi, champion of 1972 and '74 for McLaren, now with his own Fittipaldi team; Niki Lauda, champ of 1975 and '77 with Ferrari, now with Brabham, and James Hunt, winner in 1976 with McLaren, now driving for Walter Wolf racing - have a grand total of two points among them in the 1979 drivers' standings.

They are not competitive this season, with Ligier, Ferrari and Lotus monopolizing the top six places in the drivers' and constructors' standings after six races. (Points are awarded on a scale of 9-6-4-3-2-1 for the first six places.) It is not that they are lesser drivers than before, but they are driving lesser machines.

After the first timed practice over Monte Carlo's tight, demanding, 2.058-mile circuit-which affords precious few places to pass without the risk of crashing into a shop window or splashing into the harbor-Andretti was exasperated. He peeled off his flameproof suit and underwear, donned a T-shirt and cutoffs for a debriefing session with Lotus team manager Colin Chapman, then spoke at length about how complex and precarious a business is Formula One racing.

Last year, Lotus determined the driver and constructor standings from the start of the season to the finish. The Lotus '79 was hailed as a break-through in design.

The new Lotus 80 has had a variety of problems getting from drawing board to the road, however. Andretti has driven it in only one race, to date, the Grand Prix of Spain. Meanwhile Ligier and Ferrari have come up with more successful vehicles of their own.

"That just shows you how competitive and sophisticated Formula One is today," said Andretti, whose lattest problems center around the narrowness of the rims of his rear wheels, which have given him insufficient traction to negotiate Monte Carlo's hairpin turns at a suitable speed.

"There are very capable design talents on every team. All these engineers are pretty switched-on, and once you give them an idea or see something good, they can copy and even improve on it pretty quickly.

"They may not have the real creative, innovative talent that we have on the bigger teams, but they can kill you with your own ideas. Colin Chapman created the (ground effect) revolution, and now he's struggling to stay on top of it.

"So the wheel keeps turning," Andretti concluded, gesturing first at his forehead and then at his knee. "Sometimes you're up, and just as quickly you can be down." CAPTION: Picture, Patrick Depailler of France waves as he takes the checkered flag as winner of the 1978 Grand Prix of Monaco. Depailler and his fellow Formula One drivers will chase the '79 title Sunday through the twisting streets of Monte Carlo. AP