Quote:
Originally Posted by
Butterfly 
A first rate jacket I find is tailored to hang easily with only an inch or two in the gap when unbuttoned, without looking either tight or sloppy, and buttons up without undue pulling.
The fact is there is simply no rule to fall back on, other than what you feel most inclined for and what looks best with your own particular body and ensemble.
well, most "designer" jackett has this feature, my Versace/Gucci suit jacket all hung really well without buttoning and no pulling when buttoned..., so I am not sure if this is always a good indication, quality wise.
On the other hand, my St. Andrew jacket hung reasonably well when unbuttoned (that one is less structured to start with) but not to the same extend as my Versace jacket, kind made you wondering if Versace ask Zegna to sewn a piece of iron plate inside it...
I think it has something to do with how nipped the waist is and where the middle button (if 3 button) or 1st button is. If it's fairly nipped on the waist, and the buttons are mid to high, they seem to remain that particular shape when buttoned, when they're low, the jacket "spread" out wider if you know what I mean.