My bike is fun. But where do I ride?

Hey to you NW riders...

I love my new toy/machine!!! I also realize it is illegal to ride on the streets. Can anyone suggest where to ride in the Portland area that doesn't cost an arm and a leg?

Thanks all!

been thinking of taking mine to work on the weekends, good sized parkinglot, looking for a place other than that to go to myself.

just remembered where there is a closed down natures store, no cars in the lot, no ones there at all, just a big empty parkinglot...