The typical asking rate per listing is in the $30's per square foot per year. The South Loop region is going through a decrease in rates. In the last 3 months, the median rate fell $4 per sqft per year. That's a 12% decrease in rent.
Compared to the rest of the Chicagoland market, the South Loop submarket has greater rates, and you'll need to pay a premium to be in this hot region.
In the last 90 days, 12 listings have come on the market, which means listings might be going fast. You'll want to be prepared to tour spaces as quick as possible. About 8% of the office spaces in the South Loop are subleases, so you will probably need to sign a longer term lease with the landlord directly. 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 2,090 sqft. Most properties in this market are close to 3 stories. Most buildings in this region were built in 1920 and are Class B.