You can put in at Haller Park in Arlington and take out at Blue Stilly Park by the freeway. It's a good float, but a lot of rowing this time of year. That's the only one I've done, I know there are lower floats as well..

I think I'd stay above the south fork, just in case it's still pukin'. Maybe the 127th ave. launch to Haller park, or Cisero to 127th. You should be able to put the pontoon craft in just about anywhere there is access to the river.

Don't forget, if you're floating Cicero to Lime Quarry or Lime Quarry to Alington, you're on the North Fork; fly fishing only and catch-and release except for hatchery steelhead. A lot of people who apparently don't read the regulations still don't seem to be aware that the main Stilly too is catch-and-release except for hatchery steelhead, humpies and chum so be sure you let those cutthroat go.