Santiam State forest sort of around the Molalla River. Not recommended. It is a maze of logging roads, gates and (at the moment) elk hunters.
If you want something to do, I'd pick one of the four Oregon Back Country Discovery Routes. As long as the snow stays at bay, Route 3 in the Cascades from the southern border is nice until you reach Crescent. Get a premiere geocaching.com membership for $20/yr and you can grab 500 caches at a time from any point radiating out on map interface.
Thanks for the info. My wife's grandparents used to have property along the Molalla, but I don't know if we'll be over there much. That Route 3 sounds interesting though, I'll check it out!
I may also try some trails around Tillamook and/or Mt. Hebo, depending on how things work out. I never have as much free time as I'd like.
Geocaching.com memberships run $30 per year, not $20, or at least they have for the last 8+ years that I've had one. Well worth it if you need those PQs... Wait, have I been paying too much all this time?