Here's something I hadn't thought about until I saw some of the costume pics just now in this thread. My wife and I are planning on dressing as Peter Pan and Tinker Bell, right down to the shoes/slippers (I'll post pics afterwards).
Since we plan on spending all day at MK, we'll be arriving early that morning. If we show up early that morning all dressed up, will Disney still let us in? They have a no costume dress code but it is somewhat relaxed for the party. However, that doesn't start until later that day.
I'm just wondering if we should pack some regular clothes in a bag and leave it in our car, just in case.