Nancy Reagan meets kings, queens and potentates all the time, but that doesn't make reality any less fanciful for her.

"I felt like 'Anna and the King of Siam,' " she said today, likening dinner with Thailand's King Bhumibol Sunday in the fairyland setting of the Grand Palace to the experiences in the Margaret Landon book that inspired the hit '50s musical "The King and I."

Getting to know kings and queens in this three-country Southeast Asian tour has given her a chance to think about the role they play, Mrs. Reagan said en route here from Bangkok. She agreed with an American movie star who herself became a princess:

"I heard Grace Kelly say something once -- she was asked this question -- and she said, 'There's a place for monarchies. They provide continuity in a country that's important to people.' And I think she was probably right."

If Nancy Reagan can still be awed by royalty, is Ronald Reagan sometimes similarly prompted to say things like "Gosh, I can't believe I'm president of the United States"?

"Oh, yes," Mrs. Reagan said. "Yeah, yeah -- but I think that's very endearing, and I think it's important that you keep your feet on the ground."

Keeping hers there these past 10 days also has been a symbolic necessity. Behind an itinerary of romantic place names and exotic cultures, the threat of terrorism has been a sobering travel companion.

She said she was tired, and even disoriented about what day it was. Despite all that, she has seemed more relaxed and appeared to be enjoying herself with her entourage and members of the press on her plane more than on prior trips. Today her remarks were made in a short, private interview with two reporters and during a press conference that began with her rolling an orange down the airplane's aisle, a symbolic routine that has signified the end of a grueling trip since campaign days.

To Malaysians, Thais and U.S. Embassy personnel in both countries to which she took her campaign against drug abuse while Reagan proceeded to Tokyo for the economic summit, Mrs. Reagan has shown the flag with grace and guts if also necessarily from within a bubble of safety created especially for her.

"They do what they feel is the right thing to do," she said of her Secret Service details.

She learned of the terrorist rockets fired in Tokyo to disrupt the opening ceremonies of the seven-nation summit shortly after a Sunday luncheon given by Thailand's Prime Minister Prem Tinsulanond to honor her efforts against drug abuse.

She said she later telephoned Reagan just as he was going to a meeting and that he did not seem concerned. "But then he never does," she added. Talking about how they worry over each other's safety is something she avoids.

"Maybe it's having been through it once; you just don't talk about it," she said, apparently referring to the 1981 assassination attempt on Reagan. "I know what I feel, he knows what he feels. We both know what each other feel. And there's no point in having long conversations about it."

Neither does she dwell on how increased security affects her life. "Certainly over the years it's gotten more confining as terrorism has increased. But I wouldn't say it's intolerable."

The president had deflected questions about her safety on this trip by saying he was superstitious about talking of such things, and Mrs. Reagan admitted to being superstitious, too.

"I have them all," she said, listing such precautions as not putting a hat on the bed, not putting shoes above one's head, wearing something inside out if that's how it was put on in the first place, and knocking on wood.

She keeps a picture of Reagan -- "a casual pose" -- by her bedside even when she travels. Despite this solo trip, they don't spend much time apart because "I prefer to be together," though if she knows how many nights they have been apart since moving into the White House, she won't tell. The line of questioning must be for an "X-rated film," she teased, bursting into laughter.

Her longstanding loyalty to former aide Michael K. Deaver remains intact. Asked whether it is difficult to watch Deaver's troubles develop, she said "yes, of course," but she said he had not discussed the situation with her or the president.

"I'm not going to get into that," she said on whether she thought Deaver was getting a bum rap.

While traveling she had heard that Raisa Gorbachev hopes for a second summit. "I've always thought there should be," she said. "I thought we had an agreement that there would be."

She said that if the Gorbachevs come to the United States, she hopes they can see anything they want, even the Reagan's California ranch if that's on their list.

Any future mission with a diplomatic purpose, she said, will have to again be tied in with her program against drug abuse because "then I'm comfortable." At those dinners with kings and queens, she says, nobody ever talks politics to her.

"I really don't get asked questions except by the press about political things. The king and queen or the prime minister, or whatever, they don't ask you those things."