On average, listings lease in the $30's per square foot per year. The Dunwoody region is going through a a rise in rates. In the last 3 months, the median rate rose $1 per sqft per year. That's a 4% rise in rent.
Compared to the rest of the Metro Atlanta market, the Dunwoody submarket has more expensive rates, and you'll have to negotiate above asking rent to be in this hot region.
In the last 90 days, 30 listings have been listed, which means leases most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About 3% of the listings in the Dunwoody are subleases, so you will probably have to focus your search on direct office leases. There aren't many listings below 2,000 square feet posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 2,200 sqft. Most properties in this area are approximately 3 stories. Most buildings in this area were built in 1983 and are Class A.