Bike trails / loops in Portland

[johnb]

Hello Portlanders -

I will be visiting your city from Chicago in August for a wedding. I would like to stay on a few days and do some cycling. My plan is to rent a bike and either

1) take a long-ish (~200 miles) one way trip and return via Amtrak or some other method
2) do one big loop - starting and returning in portland
3) do several smallish (~50miles) daily loops

I'm really open to anything - my goal is just to see as much of the Pacific Northwest as possible via bike. I'm just starting to plan - so any advice you can give is appreciated.

Thanks.

John