It was Nancy Reagan's choice not to give the coat she wore over her inaugural gown to the Smithsonian Institution this week. "I didn't want to hide the extraordinary craftsmanship of the beaded embroidery," she said. For the same reason, Margaret Klapthor, curator of political history at the Museum of American History (and curator of the First Ladies exhibit) recently had the cape removed from the Jackie Kennedy dress in the same exhibit.

Mrs. Reagan has danced her last dance in the James Galanos-designed inaugural ball gown, now behind glass in the First Ladies Hall at the Museum of American History this week. But at least two other gowns have been removed from that place of honor. Bess Truman's original donation, a gray dress, was switched because the public didn't like it, according to Klapthor, who had stood by the case and heard the complaints. And this week a gown thought to have belonged to Abigail Adams was replaced by one definitely hers. She wore it while John Adams served as first American minister to England.

The Smithsonian once made its own survey to see if it should change the classic face shared by all the mannequins in the first ladies collection. At the same time it tested mannequins with real hair wigs instead of the sculpted variety. The old-style mannequins won out with both the public and administration staff.

"Why doesn't someone display the swearing-in costume of the first lady? Isn't that what we all know best?" asked Pat Mosbacher, wife of the former chief of protocol. "Certainly more people saw Nancy Reagan in her red dress and hat, and we all know about Jackie's pillbox."

"Suits and hats are just not as attractive on display as formal gowns," explained Klapthor. "The people in this country just like fancy dresses."

Also at the Smithsonian, Nancy Reagan got a glimpse of another salute to her fashion -- color photos and a duplicate of a white-braid-trimmed suit designed and donated to the museum by Adolfo. "I still own and wear it," she said. "You know I wear everything for 15 years."

Does the current vogue for harem pants express a wish to return to the harem? That's the question raised seriously by Stella Blum, curator of fashion for the Metropolitan Museum of Art, as she saw a few of the spring collections on Seventh Avenue on Election Day.

"Why, after all this fight for women's liberation, would women want to go back to the harem?" she asked. Blum thinks the bloomer-style pants she sees women wearing on the street and the billowy pants for home wear that designers are showing are a symbol of subservience. "Maybe it says that women are no longer interested in slugging it out on their own," she suggested.

Blum is currently putting clothes on the manequins for the upcoming "18th Century Woman" show at the Met. "Those were women who wore restricting corsets and dresses with panniers [hip padding] and Watteau pleats, and yet they dominated their century. They were intelligent, wrote, painted and could make or break men in their salons," Blum said.

"Liberation isn't always the answer. A woman can exert power through her femininity. Perhaps women have lost something coming out so strong," she concluded.

A real leopard and lion also made it down one runway this week -- at the Sheraton Washington, where I. Magnin staged a fashion show of Israeli designer fashions and American menswear for purchasers of a $500 Israel Bond Fashion Show. The lion is the symbol of Israel, "the leopard was just a special effect," said James Galfund, from the bond office, who added that about $250,000 in bond sales was raised at the benefit. Unfortunately, one of the models walked too far: Blinded by the spotlight glare, she walked off the end of the runway. Among the most applauded designs in the show were the Helen Knits, including the currently popular short knit; low-belted styles; and the Tadmor leathers.

Architecturally shaped hair, which has been showing up with many of the New York collections, is an old idea at Natural Motion, a Georgia Avenue hair salon, according to hair stylist Sara Lord. "Ordinary hair doesn't go with some of the asymmetric and geometrically cut clothes that are around today," says Lord, whose own hair is full and wavy, another option. "Clothes seem to have a lot of lines angles so hair must have sharp lines, too."

"What do you call those -- pedal pushers?" asked one Junior Leaguer as black velvet knickers with Tyrolean suspenders passed in front of her at Jaeger's spring show Thursday at the Mayflower for the league's Christmas shop. The luncheon crowd, including longtime league member Barbara Bush, liked the wearable classics and applauded the dropped waists, metallic touches and earthy stripes that spiced the collection. But what got the most applause? Two male models who wooed the women with their runway cool in everything from a non-conservative navy leather blouson to traditional black tie.

Experts from the field of fashion including a designer, retailer, New York model, and advertising executive will be among the speakers at Fashion Futures, a seminar on fashion careers to be held Tuesday evening at Georgetown University. Sponsored by Washington Fashion Group and Georgetown University School of Business, the program is geared to those interested in switching into the fashion field from other jobs, as well as those just entering the job market. The program will be moderated by Eleni Epstein, former fashion editor of the Washington Star who is now a consultant to Time-Life video. For further information on the program call Nancy Chistolini regional direcotr of Fashion Group and Woodies vice president at 347-5636, ext. 2715.)