Back many years ago before there was Fast Pass, I think I waited in line for Splash Mountain for about 2 and a half hours. I think that was the summer of '96. We were in Florida visiting relatives in Clearwater, but drove out for one day in the MK. I think that was my first chance to get on Splash Mountain, and since we were only there one day, we sucked it up and waited.
Now back when I was a kid, I remember there were some bad lines, but I can't remember how long we waited. It wasn't unusual to wait well over and hour for all of the popular rides, but we went down with the attitude that, well, it's Disney, and you're gonna have to wait in some lines. If you go in with the right attitude, it's not that bad.