Vacancy rates are soaring in Washington DC's normally recession-proof office market. Here's how experts think this downturn will play out — and why some are still optimistic.

· Washington DC's office vacancy rate has surpassed 15% for the first time. 
· Meanwhile, this recession's bailout doesn't appear to expand the footprint of government as other downturns have.
· Without government agencies and related tenants active in the leasing market, the city may not be immune to this downturn in the...