I once worked for a photographer who went to every wedding dressed in a very high end tuxedo. His rationale was that he was never under-dressed for the occasion, and usually he was sufficiently over-dressed as to make an impression on every one there.
He was also very good looking (or so I was told) and seemed to attract inordinate numbers of very good looking women.
Marketing was definitely one of his strong suits .
In my case, I used to always where either a suit, or a fairly formal dress pants and jacket outfit.
I used to base my suit/jacket purchase decisions on whether or not they had lots of useful pockets .
I also used to look for lighter weight suits, because weddings can be really warm, even when the weather isn't!