Most listings are in the $20's per square foot per year. The Littleton region is going through a decline in rates. In the last 3 months, the median rate decreased $3 per sqft per year. That's a 10% decrease in rent.
Compared to the rest of the Denver Metro market, the Littleton region has less expensive rates, so you should have no trouble finding a great deal in this depreciated submarket.
In the last 90 days, 8 listings have been listed, which means spaces most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 13% of the available leases in the Littleton 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.
The standard measurement for office space in this area is around 1,310 sqft. Most properties in this area are approximately 2 floors. Most buildings in this market were built in 1983 and are Class B.