I do a lot of fishing from my float tube. I live in Seattle, but work in Tacoma. The fishing I do from my tube is mostly bass during the warm water season, or I should say from about April- Sept. There are many great urban lakes that don't get fishing pressure for bass. Many of these lakes are small enough that they don't have actual boat launches and therefor very few people get on to the water actually. Many times it's just a couple of guys fishing power bait from shore.
I fish with guys all the time from this site. If you have any questions or comments just send me a PM. I know of a couple of lakes in the South Sound (Tacoma or thereabouts) that I am anxious to hit up this year.
The link to the Puget Sound Float Tube club that AMX posted previously,, unfortunately that group didn't really last. Nice people, not sure what happened. I was part of that while it was going.