Wifey B: "Smallest that does the job."
What does that tell us? What job? Whose job? That's the whole issue.
You have to figure out the need based on yourselves and your history. Are you spending 365/24/7 on it or part of the year? Do you still travel a bunch on land or air...you know back when that was legal and all? How active are you? Where are you and what is the climate? I can make a nice trip from home to the marina at a resort in a small boat, where we have a great bed in the bow, no bridge, but get out and go play tennis and explore when there but no way in h could I live full time on that boat. We could have years ago lived just the two of us on a small one but now we have such an extended family we need much more space.
I grew up in a house that was maybe 600 sq ft, you could feel outside air coming through the walls, no a/c, but I've been spoiled now for over 20 years and no way I could do that.
Now the bit about 60' being crew and all that. 40' can be and 80' doesn't have to be, it's what you're comfy with.
Size costs initially and ongoing. Size provides space and luxury. Size brings work with it, if you're all DIY. You gotta try some out. Now, handling, docking, those things, I really don't see any difference between 40 and 60.
Also, it's not the size of the boat, it's the motion of the ocean.
Well, something like that. Don't believe for a second size doesn't matter. But don't believe for a second that just because they're a certain size means they perform better. It's also how they use the size.