Most listings are in the $30's per square foot per year. The Tukwila region is going through a a boost in rates. In the last 3 months, the median rate rose $4 per sqft per year. That's a 15% increase in rent.
Compared to the rest of the Seattle Metropolitan Area market, the Tukwila submarket has more expensive 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 listed, which means new availabilities most likley are going fast. You'll want to be prepared to tour spaces as quick as possible. About 9% of the listings in the Tukwila 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 1,480 sqft. Most properties in this market are approximately 2 floors. Most buildings in this region were built in 1979 and are Class A.