I think 15k or higher will work. There are days you could be out when it's raining on the whole mountain. So your stuff does get soaked. Not the most fun days anyway. Gore Tex is not bad for the PNW. It is a much warmer climate for sure. When I am out there, I feel like my base layers are practically nothing in comparison to what I wear in Colorado. Seems like every time I am out there is a forecasted "Cold" day and I wear my warmer layers. I always end up burning up all day long because I am wearing too much. Fantastic riding at all the spots you mentioned. You'll like it.