Wearing a hat is no very common anymore these days. Even in the Steampunk scene there seems to be only a selection of two hats available: The bowler and the top hat. I do not count aviator’s caps in, for obvious reasons.
As you may or may not be aware of, there used to be, and basically still are, rules, of when and where a gentleman would wear what type of hat.
Some of the rules are listed here, with hats to match:
I hope you found this piece of vintage advice on correct headwear as enlighting and entertaining as I did when I found it.