The Potomac Hotel Group, the merchandising name for a group of four local hotel properties owned by real estate developer Conrad Cafritz, has opened another "all-suite property," located on Capitol Hill, in its drive to attract the corporate traveler and his expense account.

The group moved to open the Capitol Hill Suites--which like its other hotels is a converted apartment building--because it had "no place to put the overflow" of customers from its other properties, according to vice president of operations Mobashir Ahmed.

The other hotels owned by Potomac are One Washington Circle, where renovations were completed in 1976; the River Inn, on 25th Street NW near the Watergate, acquired in 1977; the Virginian in Rosslyn, converted in 1979, and the General Scott Inn, off Scott Circle, acquired in 1980. Final negotiations are underway for new acquisitions in Crystal City, other suburban Washington locations and in New York City, according to Ahmed.

Ahmed says the group has an 85 to 90 percent occupancy rate, with customers from corporations such as AT&T, Exxon, Ashland Oil, Corning Glass and Aetna Life Insurance.

"During the high demand period, our marketing strategies are geared to 5- to 7 percent of the corporate market," Ahmed said. "We don't dilute our impact by going all over the world or contacting all of the Fortune 500 companies. We have only a vital few accounts; we don't concentrate on the trivial many."

The Potomac Hotels' suites, with living and dining rooms and kitchens, are attractive to the corporate customer, Ahmed said.

Return business, he says, "is extremely high, and the average stay is longer than with most hotels. About 80 percent of our clientele has been staying with us for five years."

In anticipation of this summer's slump in local tourist business, Potomac Hotels sought to boost its occupancy rates by offering deals such as "travel agent month" during August, when travel agents could spend a "suite summer night" and participate in a "suite surprise treasure hunt" for a reduced rate of $20, compared to the normal rate of $90.

"The reason we have been sold out this summer is we were able to change our marketing plan to address weaker economic conditions," Ahmed said. "We were able to anticipate stress periods happening through the summer, to contact price-sensitive markets and start cut-rate deals."

The Potomac Hotel Group is managed by International Hospitality Group Ltd. in Columbia, Md., which also owns and operates hotels in White Plains, N.Y.; Asheville, N.C., and Hollywood, Fla. International Hospitality is also building a hotel on Baltimore's Inner Harbor which is scheduled to be completed in 1983.