Most listings are in the $20's per square foot per year. The Littleton submarket is seeing a decline in rates. In the last 3 months, the median rate fell $1 per sqft per year. That's a 3% decline in rent.
Compared to the rest of the Denver Metro market, the Littleton submarket has less expensive rates, so you should have no trouble finding a great deal in this undervalued region.
In the last 90 days, 10 listings have been made available, which means listings are probably going fast. You'll want to be prepared to make an offer immediately. About 10% of the available space in the Littleton are subleases, so you will probably need to consider the implications of signing a direct lease with the building. There aren't many listings below 2,000 square feet on the market, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 2,150 sqft. Most properties in this market are close to 2 stories. Most buildings in this market were built in 1983 and are Class B.