The two most popular places are the hill off of Imperial Highway and the Northwest Airlines cargo lot.
To get to the NWA cargo lot, take Aviation Blvd south bound. Before you reach Imperial Highway, there are some buildings to the right near the thresholds of runway 25L. Turn right at the traffic signal and then turn right again. Go all the way to the fence and park in the lot. This is a great spot to get aircraft on short finals for runway 25L. There are signs posted warning against loitering and/or trespassing, but if you maintain a low profile and not call attention to yourself you should be fine.
As far as the hill, The airport is bordered on the south by Imperial Hwy so as you leave the airport take Sepulveda Blvd. - South to Imperial Hwy and turn right (west). Go about 1/2 mile until Main Street (you can only turn left) and turn left and then turn immediately left on East Imperial Hwy. Go up to the top of the Hill and park. You will see park benches that you can sit in that will allow you excellent views of the Int'l Terminal (South side), Terminals 4 (American), 5 (Delta), 6 (Continental), and 7 (United) and the south pair of runways (25R and 25L). You'll need a good zoom, probably something above a 210mm, but it's a good spot to just sit back at watch all of the activity.
If your looking for a place inside the terminals, the Tom Bradley Terminal is good in the morning. In the Bradley Terminal, go up the stairs toward the shops and the restaurants. There are a few large windows providing good views of the entire Q and S taxi ways. You must have a boarding pass to access the gate areas in the Bradley Terminal though.
The end of terminal 1, where Southwest Airlines and America West Airlines reside are also good for watching aircraft utilitize runways 24L and 24R.
Hope this helps....and good luck!
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