The typical asking rate per listing is in the $20's per square foot per year. The Colorado submarket is going through a an increase in rates. In the last 3 months, the median rate went up $1 per sqft per year. That's a 3% rise in rent.
In the last 90 days, 1968 listings have been made available, so you'll want to check back regularly for new listings. About 3% of the listings in the Colorado 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 2,252 sqft. Most buildings in this area are close to 2 stories. Most buildings in this area were built in 1980 and are Class B.