The boat we bought was larger than we had been looking at. At Registered 50', it has at least twice the living space as most of the 45' boats we've been aboard. We've never regretted the extra space, even when it is just the two of us (and three cats) aboard. The only time I've regretted about this boat is now that we're on the East Coast, our draft restricts us from the Trent Severn Waterway in Canada. That's one of the items on my bucket list.
As Peter knows, we are proponents of a stand up engine room. Lots of room to move around and easy to get to most stuff. WAY easier to inspect/maintain/replace components, and the easier it is to get access to, the more likely maintenance is to get done, or at least that is my take on it. I'm also a fan of well maintained single engines.
Regarding the widebody salon, we were looking for a full walk around deck when boat shopping, finally narrowing our search to 48' to 49' Defevers, but we ended up getting a full beam salon boat. We don't regret it at all. There's something to be said for being able to comfortably seat 6 people at the dinette with excellent visibility outside to port and still have lots of room to move around, not to mention the two wall hugger full recliners to starboard.
Fore and aft exterior access for line handling isn't that difficult, and the payoff, especially in inclement weather is absolutely tremendous!
Obviously others may disagree, and for some stand up engine room and full width salons are not the correct choice, but for us, it was the correct choice.