I just flew out of Orlando Int'l today... I was running late, and did not arrive at the airport until 10:30 for my 12:05 flight. Between the extremely long lines to check baggage (both counter and curbside were enormous), and the huge security line, I made it to my gate at 11:45, just prior to boarding. Too close for my comfort.
(On a side note, I was flying Southwest, used online checkin, got an A boarding pass, and even though I was one of the last, I managed to get the seat I wanted, with no one sitting next to me on a nearly full flight... so it all worked out)
Two hours prior to departure time is a GOOD amount of time to get there, because you really never know what's going to happen. You might get pulled for a random security check. Even if it's a slow time, there might be delays in check in or security due to less staffing. There are plenty of stores and other things to do in the airport to keep one occupied should they get there early, and there be no hold ups.