On average, listings lease in the $60's per square foot per year. The Downtown San Francisco-Union Square submarket is going through a decline in rates. In the last 3 months, the median rate fell $12 per sqft per year. That's a 16% decline in rent.
Compared to the rest of the Bay Area market, the Downtown San Francisco-Union Square submarket has higher rates, and you'll have to negotiate above asking rent to be in this hot region.
In the last 90 days, 63 listings have been posted online, so you'll want to check back regularly for new listings. About 8% of the listings in the Downtown San Francisco-Union Square are subleases, so you will probably have to consider a longer term lease. 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 1,160 sqft. Most buildings in this area are close to 6 stories. Most buildings in this area were built in 1909 and are Class B.
Health care is the dominant industry in this area. Commute by car is the most popular way to get to work amongst Downtown San Francisco-Union Square folk. Commuting between 30 and 45 minutes a day is the norm for those who opt to reside in this part of town.