I thought it never rains in Seattle just mists :-).........a transplant from Seattle says that when she live in Seattle she didn't tan but rusted :-).........

I wear a similar setup as you.

First, I find riding in the cold rain easier than warmer rain as I have found, despite all the new techno gear out there, that breathability and rain protection are mutually exclusive. So in the cold rain, I batten down the hatches and wear rainPROOF gear and warm clothes and am happy.

I am mostly concerned about seeing and being seen so I will pack more headlight power and more reflective gear and more blinking rear lights..........

Warmth:
Head: Wool toque
Wool shirt
Yellow LL Bean shell (39 dollar cheapo Goretex knockoff) with pasted on reflective strips
Tri shorts
Campmor cheapo rain pants (on sale for 10 buck)
wool socks
goretex liners
spd compatible bike shoes
Kinco insulated work gloves (the orange ones with the reflective strip).

That is it......and when it snows and is colder add a layer on the top and switch to bike pants and add a bootie...........below zero I have switched to larger bike spd compatible bike shoes with a sorel liner inside (prevents the cold pedal and clip transfering the cold to the bottom of my foot)......cold hands and cold feet are what I work hard to prevent...........

I am lucky-get to wear scrubs at work so all I do is hang up the wet stuff and change into my work clothes...........