On average, listings lease in the $30's per square foot per year. The Falls Church submarket is seeing a decline in rates. In the last 3 months, the median rate fell $6 per sqft per year. That's a 17% decrease in rent.
Compared to the rest of the Washington D.C. market, the Falls Church submarket has smaller rates, so you should have no trouble finding a great deal in this depreciated submarket.
In the last 90 days, 9 listings have been listed, which means leases most likley are going fast. You'll want to be prepared to make an offer immediately. There aren't many listings below 2,000 square feet on the market, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 2,500 sqft. Most buildings in this region are approximately 5 stories. Most buildings in this region were built in 1980 and are Class B.