I think you'd be happiest with the Gemini catamaran.
1) It has a very large cockpit and salon for louging. Unlike a monohull, the two are on the same level—not separated by a steep companionway.
2) The Gemini already has a cockpit enclosure system designed for it. I don't believe that is true of either the Nonsuch 33 or the Catalina 38.
3) The Gemini has the largest salon of the three boats. It has a lot more usable room than a Nonsuch 33 or Catalina 38 IMHO. Not many boats <40' LOA have three decent size double cabins, and a salon the size of the one in the Gemini. If you're living aboard, you can set it up the way one of my friends did, where one of the cabins was her office.
4) The Gemini can be fitted with heat and A/C fairly easily. Personally, I wouldn't consider Seattle or the Pacific Northwest a colder clime... since it is fairly temperate there, especially compared to say New England.
5) In terms of maintenance, the maintenance costs are often related to boat size, and go up as the length goes up. They also, often, go up with older boats, and the Nonsuch will probably be of an age were replacing the standing rigging
or other major systems may soon be necessary. You can find both the Catalina and the Gemini in more recent vintages that will not be at that point.
With your budget, you could even possibly go with a new Gemini, which isn't the case with either of the other boats. A 38' Catalina would be more than that IIRC, and the Nonsuchs are no longer made.
Most marinas don't charge extra for a Gemini, since it has a relatively narrow beam for a catamaran, and can fit in a larger slip without much trouble.
We have several members, including ChucklesR, that own Gemini catamarans, that you will probably hear from shortly.
One thing to consider for living aboard purposes, is that a catamaran won't have rolling or heeling issues, and makes for a much more comfortable living space as such.
In terms of full disclosure, I am a multihull owner, and my boat is made by the same manufacturer that makes the Gemini catamaran. I've had very good customer support from them, and one of the reasons I chose to go with them for my boat was talking to some of the boat owners at several boat shows. They seemed to be one of the only vendors that actually had boat owners present at their booth willing to talk openly about both the good and bad experiences they've had.
The Gemini catamarans, like the Telstar trimaran I own, are built to a specific price point and market niche, and as such will not have the massive amounts of teak that you see on some other boats or the finest cabinetry—but they do give you a lot of boat for the money.