The marriott SFO
will give you excellent view of the landing runway. This runway is also used for the international heavy flights for take-off. This hotel will mostly let you see the airplane landing.
The Westin SFO
will also give you an excellent view of the runways too. It is the closest hotel to the actual runways. From your hotel room you will be able to see the two runways used mainly for take-off for the domestic flights. You will also be able to see the other two runways, which are used for landings in the distance.
If I were to stay at one of the hotels, I probably would stay at the Marriott just because it is a hotel that has more floors and gives great unobstructed views. Plus it is connected to a park that is very popular for plane spotting.
At around midnight & 1am you will be able to see CX
, etc, all taking off for Asia.
Make sure you get a room on the east side of the hotel.