Compared to the rest of the Seattle Metropolitan Area market, the Sumner submarket has lower rates, so you should have no trouble finding a great deal in this discounted region.
In the last 90 days, 4 listings have been made available, which means office spaces most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. 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 1,120 sqft. Most buildings in this market are close to 2 stories. Most buildings in this area were built in 2001 and are Class B.