Not to be vague, but it really depends on your route and how early you want to be at the airport. My DH insists we arrive 2 hours prior to our flight...the one time we hit unexpected traffic issue i became a convert to his way of thinking.
Anyway, make sure to allow plenty of time to get from the park (whether you're parked at the public garage or a guest at one of the onsite hotels). We typically walk out of the park gates 3 hours before our flight departs, which allows us plenty of time, including filling up the gas tank.