My family always goes to Montana for the Fourth of July, where it is legal to set off your own fireworks. Now that I'm, y'know, a grown-up and married, I drive over with my sweetie in the morning in time to catch the bad-ass parade. We eat lunch and visit the fireworks stand and try to guess what will be cool-looking and fun to light off. A word of advice: if you like fountains, either buy a bunch of really cheap $1-$2 fountains or buy a couple of expensive $15-$20 fountains. When I buy something in between, they are really lame compared to the ones that are cheap because you paid more and they're still kind of small and don't last very long.
So as it gets dark, people start lighting their fireworks in the park and when it gets properly dark, there is an official fireworks display. The whole place looks like a cheery, sparkly war zone--smoke everywhere and fragments of cardboard and plastic and grit falling on you. It's great.