Most listings are in the $20's per square foot per year. The Rosemont region is going through a decline in rates. In the last 3 months, the median rate decreased $2 per sqft per year. That's a 9% decline in rent.
Compared to the rest of the Chicagoland market, the Rosemont submarket has smaller rates, so you should have no trouble finding a great deal in this discounted submarket.
In the last 90 days, 16 listings have been listed, which means office spaces most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 175% of the available space in the Rosemont are subleases, so you might be able to snag a great spot on a short term. There aren't many listings below 2,000 square feet posted, so finding a space for a small business might be tough.
Even though the median size is 11,460 sqft, there are still 0 office spaces below 2,000 sqft. Most properties in this area are close to 11 stories. Most buildings in this area were built in 1988 and are Class A.