Most listings are in the $30's per square foot per year. The Falls Church County region is going through a a rise in rates. In the last 3 months, the median rate rose $35 per sqft per year.
In the last 90 days, 5 listings have been posted online, which means listings most likley are leasing quickly. You'll want to be prepared to make an offer immediately. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 540 sqft. Most properties in this region are around 1 stories. Most buildings in this market were built in 1980 and are Class B.