Cedar is one of the most rot resistant woods, and certainly of the local woods in Northwest. Every kind of installation would require a different approach, In my experience with boat building (the most harsh environment for rot/water damage) sealing the end grain of any board is the most important part - If you don't want ANY weather to show over the years, you would have to use a finish that develops ontop of the wood, not a penetrating finish. Cetol, or tradtional oil based marine varnishes work great but are a lot of work! If your okay with some aging/weather showing go with the pentrating oil finishes. Dalys finishes in Seattle has many options. Good luck!

These are all good suggestions. We also usually install wood siding as a rain screen - this allows for an air space behind the siding. When air can circulate, there's much less opportunity for rot and mildew to develop. However, all wood is going to change color over time as a part of the natural weathering process. Cedar tends to turn silvery over time, which is often quite beautiful - but if you want to prevent this, maintenance and cleaning will be a regular, never-ending process.