We did not think that the days before and after were really that bad. July 4th is absolutely crazy, though! If you want to be in a park, get there early and plan on staying, as I know MK reached capacity fairly early this past year and it was packed when we went early to grab one of the July 4th pins.
As pin collectors, we split up and got each of the park's special pins, then very deliberately spent the day outside of the parks. You will have the chance from many spots outside to watch fireworks (we watched the MK's incredibly ones from a distance) without being in the middle of the mayhem.