Six of Washington's top corporate leaders gathered over the weekend and said that in spite of a generally gloomy outlook for the U.S. economy, business is good in Washington and Washington is good for business.

The occasion was the second annual Ferris Washington Showcase, a forum sponsored by Ferris and Co. Inc. Featured were performance reports and predictions from top executives of the city's banking, retail, energy and real estate companies trying to attract investor interest from the 100 or so people in attendance.

Austin Kiplinger, president of Kiplinger Washington Editor, opened the forum on a cautiously optimistic note.

Kiplinger said he was encouraged by the amount of capital investment by American industry. "The U.S. is in a period of consolidation and problem solving after a 20-to 30-year spree of expansion," he said. "The period of the 1980s is going to be a period of solid growth for the U.S. economy."

For anyone involved in the Washington real estate game, 1978 was a good year. And Washington Real Estate Investment Trust was no exception. WRIT President B. Franklin Kahn recited the company's impressive record: a 17 percent compound annual growth rate, every property it owns has been successful and the company has doubled its equity on every property it has disposed of.

Next year will be the 75th anniversary of People's Drug Stores and, according to the chain's president, Sheldon W. Fantle, "The future is too exciting to contemplate."

Fantle pointed out that People's is number one in 60 markets. Sales for 1978 were up by more than 10 percent and earnings jumped by 37 percent over last year.

"There is a new dynamic movement from Northern Virginia to Baltimore on the concept of a Baltimore-Washington regional common market,"said Robert F. Tardio, chairman and president of Suburban Bancorp, the $1 billion bank holding company.

According to Tardio, the key to the development of the area's economic potential is "money in motion" -- new money being invested by private industry.

According to Washington Gas Light Co.'s chairman and chief executive officer, Paul E. Reichardt, last year was a "disappointing" one for the company, but he assured the audience that the local natural gas supply is "good and improving."

Riggs National Bank is a formidable Washington.institution. With $2.4 billion in assets, 25 offices and more than $18 million earned last year, Riggs holds one-third of all banking business in Washington.

"The Washington market is one reason we're enthusiastic about our earnings," said the bank's chairman, Vincent C. Burke Jr. Burke pointed to a steady growth in employment and median family income as evidence of the increasing economic strength of the city.

Martin Marietta Corp. President Thomas G. Pownall said that the prospects for this year are good but he underscored that the danger of a recession by saying "I hope we as a nation don't become so obsessed with the possibility of a recession that we scare ourselves into one."

A second forum will be held Saturday from 9 a.m. to 1 p.m. at the Shoreham Americana. Chief executives of Marriott Corp., Geico Corp., American Security Corp., Giant Food Inc., Woodward & Lothrop and The Washington Post Co. will participate.