Brooks Brothers - the arbiters of all things preppy introduced a style of suit in the 1950s which was markedly different in cut from the English suits then being worn by East Coast establishment figures.
The Brooks Brothers "Sack Suit," also known as the
Ivy League look, was boxy, not fitted - straight up and down, not tailored at the waist. The shoulders were softer and narrower, not as stiffly padded as those in upright English models. The jacket was relatively short, particularly by today's standards, and had one centre vent. This comfortable if unsexy suit became the uniform of the American businessman, and it definitely influenced Italian designers, who also produce loose and less stiffly constructed suits.
However, there are so many variations in suit design these days, across all national borders, that it is hard to identify one particular national style.
Brooks Brothers probably still makes these square 1950s-style suits. I wouldn't know - ask your dad.

Double-Breasted Suits
These always seem dressier to me, and flashier, than other suits. They are often favoured by portly men, as their uniformly cylindrical silhouette camouflages the bulbous figure. But I think they look slick on slender men, too, particularly if they are fairly fitted.
Here's the tricky thing to note about doublebreasted suits: the number of buttons varies. Again, the more modern the suit, the higher the buttons will go, and the less shirt-and-tie will be exposed. There are two rows of buttons, and only some of them are functional. When salesmen say "four on two, " they mean that there are four buttons on the front of the jacket, but only the bottom two are below the fold of the lapel. The top two will not be functional, nor will they be lined up vertically with the bottom two.
This will be a very out-of-date, r98os-looking suit.
(Think American Psycho.) "Six on four" is the more common model today: it means that there are six buttons on the front of the jacket, with four of them below the end of the lapel. This produces a higher gorge, and a narrower silhouette. This is the design favored by the Prince of Wales, and he looks damn good in it. The trick of it is to have quite a high button stance - that is, the suit will look quite stern and tubular, not droopy and relaxed.
Note that on the Prince's suits, the lapel rolls up on the chest, not below the waistline, as with old fashioned six-on-two configurations.
If you want to look really natty, try a six-on-six double-breasted. (You had better be tall.) All six buttons are (or appear to be) closed. This look was popular until the 193 0s. It looks a little fussy and military today, but also nostalgic in a way that can be dramatically stylish.
Double-breasted suits nowadays always have peak lapels, double vents, and fairly pronounced
shoulders.