I think Fourth of July.
But that's because I hail from The Continent.
Down here on the south Peninsula, New Year's Eve is the big night. For one it gets dark earlier, but the bigger reason is the cool (yet warm by Northern standards) weather plus the low chance of rain, i.e. it's our meteorologic dry season.
Does Naples have fireworks on the Fourth of July.
Come to think of it, I'm not sure. The past couple summers we've been away, but even if we weren't I'm not sure I'd want to go with it getting dark so late, the high chance of summer rains, plus the inevitability of those dastardly mosquitoes, too.
Have a happy, healthy and hydrologic 2012!