Pioneer Square
On the corner of Yesler Way and 1st, its where the bands and pubs are.
And yes, they have a BB Kings Hideout.
See the Google Map. Or visit them at: pioneersquare.org/

Speidels Underground Tour of Seattle
I've heard this is a must see attraction. The old store fronts are still there. Its on 601 1st Ave. See the Google Map or visit them at undergroundtour