I hear July 4th is one of the worst days to be in WDW altogether because so many people go!
I would think you'ld find it was a bad idea, if people are not busy packing the parks, you can bet a load will pop off to Tyhoon Lagoon and Blizzard Beach to have a soak in the hot Florida sun. Not to mention the fact it's a weekend!, Your possibly better off picking the day before or after July 4th. As the crowds wont be so bad.
Are you staying within the parks or outside? If you have a rental car or anything I suggest taking a "break" day outside the world. Point Mall (or "that place that used to be called Belz Mall") and Florida Mall are always nice places to go and just browse if you want (Not to mention Point has an amazing chinese counter in their food court!). Or just go to Downtown Disney and look around there and maybe take the boat to the Old New Orleans and Floridan resorts? The atmosphere around those resorts is quiet and romantic in a way.