I bought my boat on the east coast and brought it out to the PNW. It was built in the PNW, but for the east coast, so had two AC units. In the brief few days prepping the boat to come west, the AC was a life saver. Once here, I've used them on only two occasions that I can recall, in 4 years, and not really necessary then.
But: in the PNW humidity is the enemy. Running AC in the humid east, you get dehumidification for free. When I got the boat here, I removed one of the AC units and installed a "whole house" dehumidifier that blows throughout the boat using the existing AC ducting. It has been absolutely brilliant. Using only 400W when on, and running at a fairly low duty cycle, we keep it on a lot of the time, running from batteries even at anchor. Towels dry, nothing feels clammy, no mold, windows don't fog. It keeps the relative humidity at about 50-55%. Shut it off on a moist rainy day (and there have been a LOT of them this year) and humidity climbs into the mid 70% range, windows fog, towels don't dry, upholstery and bedding feels clammy.
If I was ordering a new boat for the PNW, it would absolutely have the AC ductwork installed, and a dehumidifier blowing through them.