When I was talking to a friend of work, he highly recommended doing the Under the streets tour. We booked it in on the second day we were in Seattle and when we booked, we were the only ones on the tour.
When we turned up, we were the only ones there. Prior to the tour starting, 2 other couples turned up so we had a tour of 6.
Our tour guide, Richard, gave us an insight of the history prior to us starting the tour. It was really interesting. To see the sub level right under the street level was excellent. Richard, the guide was really informative and gave some really funny anecdotes along the way. The tour went from underground to outside and then to back underground a block away.
The tour, as the guide said was in an area that was a little dangerous due to the socio-economic climate and we had to be a little careful in the area.
Other than that, our tour guide Richard was funny and informative and made the tour really enjoyable.
If your in Seattle, take the tour, it was really good and gave a unique insight into the cities history.