Most listings are in the $30's per square foot per year. The Tukwila region is experiencing a a rise in rates. In the last 3 months, the median rate went up $4 per sqft per year. That's a 15% increase in rent.
Compared to the rest of the Seattle Metropolitan Area market, the Tukwila region has greater rates, and you'll need to make a great offer to be in this hot region.
In the last 90 days, 23 listings have been posted online, which means leases most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 9% of the office spaces in the Tukwila are subleases, so you will probably need to sign a longer term lease with the landlord directly. 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 1,480 sqft. Most properties in this region are around 2 floors. Most buildings in this region were built in 1979 and are Class A.