‘Do whatever works for you’ is the very best advice of all.
To me it’s not a question of whether a full width design gives a larger salon than one with walk around side decks. Of course it will. For me the relevant question isn’t ’is it bigger,’ but
how much is enough?
The attached pics show the interior salon on my Helmsman 38 Sedan (LOA 41’, bean 13’11”), along with the 20” wide covered side decks. Yes, a full body design would have been even bigger, but for our use this cabin size was more than enough.
All boats are a compromise. Unless you have Jeff Bezos money any boat requires trade-offs and prioritizing some things over others.
I’ve owned one ‘wide body’ boat and wouldn’t do it again. Doing a trapeze act on the 3” wide toe holds to hang fenders and handle lines was going to result in unplanned and unwanted swims (someone I know with the same model boat has had multiple such aquatic adventures).
Another boat I owned had narrow side decks, about 6” wide. The only way down them was feet in line. One time trying to move quickly to push off from being blown into another boat my foot got caught in a rail mount and tore the meniscus. Painful lesson learned.
Since then one thing I’d been unwilling to compromise on was deck access, safety, and utility. I’d rather trade off a little less cabin space for being able to quickly, easily, safely get to any part of the boat. But that’s just my personal trade off, we all make our own that work for us.