Scott, check out my ridewithgps account, I've mapped out a few rides in those areas. PLEASE NOTE that some of these have not been ridden in awhile so it's rider beware! The Banks - Vernonia trail is very nice but not suitable to high speed riding (and there are some gravel patches). I ride a Long Haul Trucker with 700x37 tires so packed gravel and dirt is not an issue.
http://ridewithgps.com/users/771