In the really old days they had an observation deck where you could go and watch for free in the airport. They piped in the tower's radio traffic as well.
I do remember that it cost like a quarter or something last time I went up. I found it pretty neat too bad the world is like it is now and we can no longer do that.
One of the things that I used to like to do was to park along Portland about SW 74th and watch the planes, even though it was only an endless string of 737s and MD80s. Unfortunately, after September 11th, the powers that be, in their infinite wisdom, posted signs along that stretch prohibiting parking :roll:. I would like to offer an alternative place, but I am unaware of one.
Sorry man no luck these days... I take aviation maintenace at metro tech right at the airport and see the stuff everyday. You could always go out on that gravel road on the south side of the airport and park along side the road and hang out there.