Highway 6 is not a bad option - not as quiet & scenic as the Nestucca, but a relatively low traffic route to the coast:
http://www.portlandonline.com/transp...ex.cfm?c=39889
make sure you take the 3 Capes scenic route via Cape Meare out to Cape Lookout from Tillamook - it's a little extra climb & a little longer but really an exquisite ride. Of course, it's easy for me to tell you all to do a little extra climbing, i haven't just ridden 60-some loaded miles...
And, for places to stay in Forest Grove (just a few miles west of Hillsboro), you might want to try McMenamin's Grand Lodge.
http://www.thegrandlodge.com/index.php?loc=59&id=464