As a musician, I had the good fortune of being invited to NAMM a couple years back. It was a great convention. I truly enjoyed having the opportunity to visit and intermingle with musicians (both known and unkown) of varying calibers. And of course, the added benefit of not having to pay parking was a plus. But yes, there may very well be a spike in attendance at the parks (it's also MLK Day on Monday). Traffic will definitely be heavier, and the nearby Disney lots will be more full.