I'll add more detail to what As739x already said. The park on the eastern side of runway 1's is called Bayfront Park. This is right across the street from Westin Hotel. There's also a free parking area on the Westin lot for park access... make an immediate left turn as you enter the hotel and the parking area will be on your left.
From there you have unobstructed views to runway 1's:
and the eastern part of 28's:
Or you can also park at Marriott Hotel just further east. There's a jogging/bike trail that runs along the bay. If you walk further east you can see rwy 28's threshold. There are some nice restaurants there with views to rwy 28's (Elephant Bar, El Torro Mexican, etc).
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Photo © I. Gunawan
Another viewing location is the Millbrae BART/Caltrain station parking structure (also on Millbrae Avenue) directly across 101.
If you want to go up the hills, you can try the Millbrae hills on the south side of the airport. The area is residential area and you can drive around to find a good view. I've been there only once before and I can't remember the details.