What? No-one mentioned Miami Vice (the series)?? :)
Ok, seriously.. there are hundreds of films from the 40s-60s with great suits. One of the things i love about this era is that pretty much everyone was wearing a suit, whether you were a shop assistant or truck driver. Not like the aesthetic nightmare we live in now...
From "Room at the Top", for example:
And then when they actually dressed up... wow. "My Fair Lady":