Average asking gross lease rates in Downtown Seattle are up a full percentage point in the fourth quarter to $25.95 per sf, according to CB Richard Ellis Inc.'s local office report. In the Eastside submarket, asking gross lease rates inched up to $22.87 per sf. Meanwhile, Colliers International pegs fourth-quarter vacancy in the 21-million-sf CBD at 13.6%, 30 basis points higher than the third quarter.

However, the tide is not about to turn toward an owner's market any time soon, Grubb & Ellis cautions.

"Even though vacancy has stabilized, rental rates may decline further until there is significant demand," according to the Grubb & Ellis report. "Landlords are competing with a large amount of sublease space, which continues to affect pricing.