On average, listings lease in the $20's per square foot per year. The Great Falls region is experiencing a an increase in rates. In the last 3 months, the median rate increased $21 per sqft per year. That's a Inf% increase in rent.
Compared to the rest of the Washington D.C. market, the Great Falls region has smaller rates, so you should have no trouble finding a great deal in this discounted submarket.
In the last 90 days, 1 listings have come on the market, which means spaces most likley are going fast. You'll want to be prepared to tour spaces as quick as possible. 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 1,500 sqft. Most buildings in this market were built in 2000 and are Class B.