Western WA climate and building options

I'm in south Snohomish county. I built a 24'X34 enclosed garage, might be too small for your needs. I used a concrete slab and wall footings, an 2X6 studs. R-34 insulation in the walls, and 2 layers+ of R-19 insulation in the ceiling. It has it's own 200 amp feed. I'm in the middle of a town, so this is as big as I could go on my city lot. It stays dry, RH less than 40% with only a small space heater. Never gets below 55 degrees, even if it's 20 degrees out side. The auto bay is shared with my wife's Pilot, and my 70 Swinger 340. The rest is taken up with my machine/wood shop. I believe the key is in the thickest walls you can afford, and the most insulation you can put in it. JMO.