With their visitors' map of Washington spread on the grass off 15th Street near the Washington Monument, Jaime and Elizabeth Gonzalez and their five children were debating, in spirited English and Spanish, how many tourist spots could be visited in one Fourth of July.

At midday on their one-day visit to Washington for the nation's 206th birthday, the Gonzalez family of Brooklyn already had been to the July 4 parade on Constitution Avenue, to the Museum of Natural History, the Capitol, the Washington Monument, and to the Festival of American Folklife on the Mall.

"There is so much to do. This is a very special place on the Fourth of July," said Gonzalez, an auto mechanic who had packed his seven-member family into their 1975 Ford Torino for the five-hour drive.

The Gonzalezes decided on Arlington Cemetery, with plans to return to the Monument grounds for the afternoon's musical show. Maybe they'd even stay for the fireworks near the Washington Monument before heading back to New York.

And so it went yesterday for thousands of tourists and area residents who faced the task of deciding how much of the music, food, fireworks, parades and other holiday festivities could be crammed into one sun-filled Fourth. Warm, breezy weather also made it ideal for hundreds of thousands who headed for the beach and for countless others who marked the day with backyard barbecues.

Starting with a morning crowd of 25,000 who lined Constitution Avenue for the three-hour-long parade of marching bands, militia in Revolutionary War-era uniforms, antique and modern automobiles and other Americana, the Mall filled steadily with visitors celebrating America or just looking for fun.

By nightfall, a crowd of about 300,000 people -- smaller by at least 100,000 than July 4 gatherings of the past two years -- had gathered on and around the Mall to watch the traditional mammoth fireworks display and to listen to a performance by the Washington National Symphony at the west front of the Capitol.

District and U.S. Park police described the crowd as peaceful and generally well behaved, and said that traffic in the area dispersed swiftly and with "no problems at all."

Spokesmen for Metro, which added special single-fare bus and subway service to help carry away the large crowd, reported what they described as only "minor problems" and slight delays in its operation -- an assessment disputed by some subway riders who said it took them hours to get home.

Metro officials acknowledged that four trains -- three on the Blue-Orange line and one on the Red line -- malfunctioned and were taken out of service at the height of the homeward crush, but said that none of these problems should have resulted in schedule delays of longer than 15 minutes.

"It's unfortunate that it took some people that long," said Metro spokesman Cody Pfanstiehl, "but I think that most of the crowd backups were outside the stations, and even with trains running perfectly on time, a crowd that big is going to have to wait in line awhile.

"As hard as we try, there's no way you can get home on the Fourth of July as easily as you do on a normal day."

The chief Metro problem noted by reporters at the scene occurred at the Smithsonian subway station -- the nearest to the Mall and a usual post-fireworks bottleneck --where some of the crowd waiting outside the entrance for the platforms to be cleared began pushing and shoving.

Some persons in the crowd were knocked to the ground, but none appeared to have been injured, Metro employes said.

Earlier in the day, as she watched the parade along Constitution Avenue, 17-year-old Margaret Harrison of Alexandria frequently hopped from the curb into the street to capture the more colorful sights and sounds of the extravaganza on her video recorder.

"I want to have this to remember," said Harrison, whose family will be leaving shortly to return to their native Nigeria after a 10-year stay in the United States. "It's colorful and it's special."

"It's fun . . . and it's a chance for the kids to see all this history," said Michelle Blackwell of Rochester, N.Y., who used the occasion of a business convention to bring her four children sightseeing here for the Fourth. "I don't normally feel patriotic, but this makes you feel this is the best country to live in, especially when so many liberties are being taken away from people in other countries all over the world."

The political perspective was different, however, at a July 4 "Smoke-In" at Lafayette Park, at which the American flag flew upside-down and some 500 persons protested against what they called repressive enforcement of the nation's antimarijuana laws.

Carrying a 10-foot-long facsimile of a marijuana cigarette, the youthful protesters burned hundreds of blank Selective Service registration forms and then lit joints.

U.S. Park Police arrested nine persons on charges of sale and possession of marijuana, although most of the arrests came before the start of the demonstration, at which few arrests were made. Police said they had arrested more than 70 persons during three days of demonstrations by the group.

Parade fans got their fill at the massive July 4 parade, featuring some 4,300 participants in more than 100 units that ranged from Little Miss Spotsylvania to the Marching Bobcats of Western Dubuque High School of Epworth, Iowa.

"It's the biggest thing in these kids' lives right now," said Larry Stoner, director of the 157-member Monticello High School Marching Sages of Monticello, Ill. The Monticello students and the band's boosters club raised $45,000 to pay for the trip, while the local school board provided another $36,000 for the new uniforms and equipment.