Andrew,
Since you're going to be in Eugene, take Michael Dugger's suggestion and play Tokatee, which is an hour or less, east of Eugene.
While Tommy Naccarato will take me to task, I think it's worth the trip.
Then, if you're driving from Eugene to Bandon, you have to go through Florence, Oregon, so play Sandpines.
For that suggestion, Michael Dugger, Tommy Naccarato and a host of others will rail at me.
Astoria is TOO far away from Eugene, but, I'm told it's a must play if you're in the Portland area and Noah's Ark has docked.