One of the first things that you learn with plane spotting, is that timing is everything. You not only have to be fast with your camera, but you also need to be at the right spot, at the right time.
Depending on the day of the week and the time of day, you could be standing there for a good 15-30 minutes before anything lands or takes off. In addition, you could end up with a bunch of photos of Dash 8s before anything really interesting shows up.
Therefore, before you go out, check to see what is coming in/taking off and when. However, if you want to hang around for half a day not knowing what will come or go, you will surely get photos of some interesting aircraft.