If you really want an amazing 4th of July show...
Watch "Fantasy in the Sky" in the MK on the 3rd, then on the 4th, watch the fireworks in MGM (these are rare and great!). After the MGM fireworks, book it over to EPCOT via the walkway and catch an awesome extended version of "Illuminations". We did this last year, and it was truly unforgetable!
Whatever you do, don't miss the MK fireworks--they are amazing and go off from five different spots on the 4th (and 3rd). So if you're not able to do the MK on the 3rd, save it for the 4th. Also, if you make it over to EPCOT, be sure to walk around WS after the show--the America pavillion is beautiful during this time, and if you look across the lake at SE, there's a special laser message on it! Have a great time--this is the first 4th I've missed in several years--can you tell I'm going to miss it?! =)
I'm looking forward to the New Year's fireworks now!