Re: Hanging "dress clothes", suits and such, in the boat
It's not only wrinkle free you need to be worried about... it's also moisture, smells, possibly mildew etc. I think this is a problem generally for office types that choose to liveaboard.
We keep things in large zip loc bags if we want them fresh and dry, but this is mainly guest/spare bedding and linens and such, we don't liveaboard full time and when we do it's mostly summer conditions and in any event suits are not in my repertoire anyway... I don't imagine the ziploc bag idea would do for you. There are also vacuum bagging options to reduce bulk, but again same issue. It would work to minimize space taken for undergarments and such, perhaps.
I suspect for the space you're talking about you'll need to focus on the upper range of your hunt.. few 30 footers will be able to provide what you need.
We've also noticed that most full time liveaboards (in the PNW, anyhow) will use shore facilities for showering to avoid the humidity in the boat. Inconvenient but overall the better choice long term.
One boat that does come to mind with the space you'll need, often priced in the 37 foot range with a spacious aft cabin is the mid 80s Hunter 40.. it has a double walkthrough to the aft cabin, one of which might be sacrificed for extra storage/closet space. Big boat, though, when it comes to all the other stuff (moorage, rigging, paint, etc...)
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)