Compared to the rest of the Seattle Metropolitan Area market, the Mercer Island submarket has higher rates, and you'll need to make a great offer to be in this hot submarket.
In the last 90 days, 1 listings have come on the market, which means listings most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 100% of the listings in the Mercer Island are subleases, so you might be able to find a shorter term or below market rent. 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 1,460 sqft. Most buildings in this region are close to 2 stories. Most buildings in this area were built in 1982 and are Class B.