Treating (or not) Doug Fir Posts and Beam under a roof – GreenBuildingAdvisor

I received such spot on advice for a roofing question I figured I would ask the other one that was puzzling me…

I have a side “shed” style roof under the eave side of the main gable roof of a 26×16 accessory structure.  The side roof is just intended to cover the front door and provide some cover for wood, and odds and ends.  The ground under the roof will just have pea stone.  I am not intending on putting a gutter on the roof.

The roof is supported by 3 6×6 Doug Fir posts and a triple 2×6 beam.  The posts are supported by Simpson CPTZ Concealed Post Ties, which are anchored into concrete.  The rafters are 2×6 24″ OC doug fir and the rafter tails will be exposed (i.e., I do not plan to put any facia up).  I will treat the ends of the rafter tails and triple beam.  I did not treat the ends of the posts, unfortunately.  I live in Hudson Valley New York that gets a decent amount of rain and some (though less and less) snow.

I will get some splashback on the posts and some blowing rain on the rafter tails, but most will stay largely dry.  (We just had some rain and wind so I could see what occurs.)  This is not a forever structure (we intend to sell the parcel it is on in 3-5 years), but I want to preserve things appropriately.

I like the look of the untreated fir, but suspect things will go south quickly without some treatment.  But once I start treating some parts, I suspect I will need to treat all parts to make things look OK.  

So, I was wondering what a future would look like if I did not treat any parts.  Will the posts rot quickly?  Rafter ends start splintering and checking fast?  If untreated, would I be good for a while more than 5 years?  If treating is prescribed, what is a good product that will not take away much of the natural beauty of the wood?

Thanks for any advice you might have.