Nothing last under the rain and sunshine, even sunshine in Portland.
I really like a penetrating oil like Penofin. I use it on lots of decks and have had great result. Again, I can only speak for socal weather as I have no experience elsewhere. if you are looking for a clear coat, then I would woould look at a finish by General Finishes. I have had great result with all their products. You need a flexible top coat that will expend and contract with the lumber. I have tried marine varhish but we also get the crappy Ca formula (not sure if there's such thing as we almost never use varnish anymore). Boat builders have been using epoxy (can be brushed on) for a long time. It looks a little like plastic, if protection is your priority. We did an exterior kitchen finished with epoxy (I suggested based on their requirement on durability) on all lumber. It was a bit shiny and the owner looooovered it. Myself, not so much. I like oil for a none intense, more calming look.