I dress to the occasion & place, and what the others are wearing. It is as much a mistake to overdress as to underdress.
Must places I go these days I just wear the gay uniform in South Florida -- cargo shorts, T-shirt, sandals or joggers. And that's what everyone else is wearing.
At night, though, you see more guys in long pants at the bars & restaurants, and the T-shirt is usually a darker color. But the pants are just jeans or some other cotton.
The next step up is slacks & polo shirt, or casual button. That takes care of most functions I attend, and ordinary restaurants, which again is typical in South Florida, where casual rules. Beyond that is sports jacket over open collar, and finally a tie and often a suit, like for a charity dinner or special reception. Finally there is black bow tie, for fancy galas.
I do love to dress-up, too, but I hardly get the opportunity down here. I actually wore my tuxedo more often in the Upper Midwest Plains states than I do in the Fort Lauderdale area, despite all the socializing I do here, and events I attend.