To further 'splain....
When you check in, you are given the option (which many people use) of placing a credit card on your room for "express checkout." That means that at 6AM on the day you check-out, they'll hang an envelope from your room's door handle. That envelope contains your "bill" (really more of an invoice, since all the charges have been applied to your card already). As long as everything's in order (they don'ty accidentally show that you bought a blimp and charged it to your room), you just skate out the door and head for the house.
So... not as many folks fighting to check out at the front desk as you might think. Having said that, it's still all in the timing. If you get there right as a Magical Express bus comes in, it may take a while. The longest I've ever had to wait was about 20 minutes, but that was at Pop Century when all the locals were trying to get a place to ride out Hurricane Ivan (which missed, by the way).