I used to love planespotting at SFO, especially in the days when unticketed people could also go behind security.  I would go to the old international terminal which had a nice fountain inside and faced the main runways, at the perfect point where the jets would rotate.  In Narita and Frankfurt I went to roof top observation decks which were nice, to listen to the sounds of the jets as they took off.  Baltimore also has a good indoor observation deck which I would enjoy back in the days when it was a USAirways hub.  I either flew USAirways or Southwest nonstop between Baltimore and Phoenix, or Baltimore and SFO, with Baltimore being my preferred DC area airport to fly in and out of because of its observation deck and in terminal stores and eateries.

John