Modest, simple dresses by day (many of them chemise shaped) and classic suits and extravagant, show stopping dresses for evening (with oodles of ruffles and bareness) proved to be the dominating themes of this week's round of spring couture fashion shows in Paris.

Hubert de Givenchy chose the mansion of Spanish interior decorator Alberto Pinto to show his clothes. And Emanuel Ungaro put his best designs forward at the Jacquemart Andre Museum, once a lavish private home. A chamber music trio playing Haydn replaced the usual blasting tape music.

Rarely are Paris couturiers so practical in their designs, but this season they have consistently keyed their daytime clothes to non-flashy, almost simple clothes, often given an innocent expression with white or ruffled collars, contrasting narrow belts, innocent prints such as flowers or polka dots or stripes, and youthful knee-length hemlines.

Evening clothes are quite another mater, looking not only fanciful and daring, but well worth their $2,000 minimum price tags. (Many of the daytime things, made to order for customers, start in four-digit figures.) Ruffles, beading, planned prints, embroideries . . . all the things that make clothes look as expensive as they are, were put to use.

To add to the sense of drama for the evening clothes, Yves Saint Laurent showed several uneven hemline styles, short in front, long in back. He subtly used the up-and-down technique to inject movement into some of the evening things as well.

Paris couturiers don't count on heaps of business from these couture shows. At the current price level and the current economy, the couture customer is a diminishing breed.

But many of the designers were able to trot out their best prospective customers and place them in the front row. Princess Caroline, whose mother is Princess Grace of Monaco and a Dior customer, was at the Dior show, and Valerie Anne Montassier, daughter of the President of France, was at the Jean Louis Scherrer show. Montassier's mother is a big Scherrer fan. So is Pat Kennedy Lawford who attended the Scherrer show wearing a Kennedy '80 button.

Donna Hartman, wife of the American ambassador to Paris, was in the audience at Chanel, long with Claude Pompidou, Bernadette Chirac and Eva Barre -- all wearing Chanels.

But Yves Saint Laurent, who may well capture the most customers in this 25-person league, also captured the best looking crowd. There were the wealthy French, including Olympia de Rothschild and Marie-Helene de Rothschild; Princess Feryal, whose brother is King of Jordan and Diana Ross and Zizi Jeanmaire, who found lots to talk about with each other during the show.