When the Fiberglass Fabrication Association picked the Washington area as the site for its annual convention this year, it had hundreds of hotels to choose from and could have picked a spot within walking distance of the Washington Monument. Instead, it selected a large new hotel in Arlington's Crystal City.

"The members are not big-city folk," said Sandy Heydt, the association's executive director.

"We had them outside the city because we hoped they would be less nervous about bringing their families."

More and more business organizations are looking to the little county across the river as a convenient, easily accessible and less urban location than the District to hold conventions and accommodate business travelers.

For the seventh consecutive year, more money was spent last year by travelers in Arlington than by travelers in any other Virginia jurisdiction.

According to figures obtained last week from the Virginia Division of Tourism, tourists and business travelers spent more than $477 million in Arlington during 1984.

Arlington was followed by Virginia Beach with $287 million and Williamsburg with $272 million. Travel dollars spent in nearby jurisdictions were: Fairfax County, $241 million; Alexandria, $159 million; Falls Church, $11 million.

The study, prepared by the U.S. Travel Data Center, defines travel dollars as money spent by those traveling 100 miles or more.

Mike Cannon, an economic analyst with the center, said about $95 million of the total figure falls under the category of air expenditures, the majority of which is generated by National Airport.

Seventy-five percent of the cost of tickets purchased by travelers leaving the airport and 25 percent of the cost of tickets purchased by those arriving at the airport count as travel dollars.

Rental car fees and airport taxi fares also are listed as air expenditures.

"National Airport has helped our travel industry in that it has created a demand for offices and hotel facilities near it," said Francine Bradshaw, director of Arlington's Visitors Service.

According to Bradshaw, the county currently has 32 hotels and a total of 7,000 hotel rooms.

By October, Arlington will have two more hotels and another 500 hotel rooms, she said.

"The business traveler is a very important part of our economy," said Bradshaw, who estimates that 63 percent of Arlington's tourist dollars last year was generated by business travelers.

Arlington's hotels, made easily accessible to the airport and other parts of the Washington area by Metro, have an average occupancy rate of 77 percent, the highest in the Washington area, Bradshaw said.

"Tuesdays and Wednesdays you can almost count on selling out," said Bonnie Donohue, reservations manager for the 452-room Crystal Gateway Marriott, one of Arlington's largest, newest and most expensive hotels. Arlington's hotels, made easily accessible to the airport and other parts of the Washington area by Metro, have an average occupancy rate of 77 percent, Francine Bradshaw said.

Donohue said that business travel reaches a peak during the middle of the week and stays constant year round except during midsummer and the holiday season.

"Right now we're into families," she said.

Bradshaw said about $107 million was spent by business travelers on hotel rooms alone last year. She estimated that about half that amount, $54 million, was spent in the county by those same business travelers on food.

Mike Cannon estimates that close to one-third of the total $477 million, about $143 million, was spent in the county last year on food by all Arlington travelers.

According to Bradshaw, Arlington has 330 restaurants.

"People come from New York City to eat our Vietnamese food," she said.