I don't know Willamette enough to comment on the dzlater's question (I don't care for it unless it is fresh). With 4 really good hop varieties in the kettle, IMHO I don't see the point of introducing it in the dry-hop unless there's some really smooth blend being worked out.
With HoosierBrew's suggestion of using Simcoe and Centennial, that's a really nice combo. Plays nice together.
dzlater - what did you go with?