If you're willing to forgo seeing the fireworks, make a reservation for the latest time they will take them (usually right around the time they start) and eat dinner during the fireworks. When you're done and ready to leave, the park will be nearly empty and you'll have an easy time getting out.
We ate in an EPCOT restaurant once during the fireworks (seated just as they were starting).. It took us about an hour to eat our meal. By the time we left World Shocase was a ghost town. It was real fun to slowly walk towards the front entrance and exit the park...