The typical asking rate per listing is in the $40's per square foot per year. The McLean region is going through a an increase in rates. In the last 3 months, the median rate went up $4 per sqft per year. That's a 10% rise in rent.
Compared to the rest of the Washington D.C. market, the McLean region has higher rates, and you'll have to negotiate above asking rent to be in this hot submarket.
In the last 90 days, 12 listings have been posted online, which means leases are probably leasing quickly. You'll want to be prepared to make an offer immediately. About 75% of the listings in the McLean are subleases, so you might be able to find a shorter term or below market rent. 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 1,450 sqft. Most properties in this area are close to 3 stories. Most buildings in this market were built in 1980 and are Class A.