Plenty of places. There are even mini restaurants next to the runway fence. You can eat/drink and watch the planes all day. There are some benches near the airport fence as well where you can sit alone away from train/plane spotters :-)
I can't really explain how to get to them.
There is even a runway that is intersected by a fenced public road...you can see the underbelly of incoming planes literally seconds before they land. It's an amazing sight. Bloody loud as well. You basically see all these planes lining up to land. Them come towards you and it feels like they are going to land on your head. You will love it man!