There's an odd L-shaped alley through this block, hence the L-shaped hotel in plan.
Here's a 260-meg presentation about a 34-story hotel planned on the other side of the alley, in the vacant portion of the block shown in the pics. It'll integrate operationally with the Hyatt Regency.
http://www.seattle.gov/dpd/aboutus/n...6&b=s&a=howell