To clarify my comments about spacing on finals: I was meaning staggered spacing. If the runways are too close for parallel approaches with the a/c 'side by side', then they can be staggered, at the same speed, with 2nm longitudinal spacing, but on the // runway. They would still have the required spacing of traffic ahead on their own runway, but staggered from the neighbouring one and thus achieve not lateral conflict. It would be necessary for the respective GA routings to ensure sufficient separation.
At SFO, there are two kinds of simultaneous parallel instrument approaches that can be used:
1. Independent offset approaches (SOIA), with 28L using ILS PRM while 28R on the LDA PRM (or their RNAV equivalents). But SOIA is not an option in "hard IFR" because the LDA PRM minimum is fairly high (> 1,000ft).
2. Dependent approaches. SFO has authorization to conduct staggered approaches with 1.5nm spacing between aircraft on the parallel runways. In this case both 28L and 28R can use the normal (non-PRM) ILS approaches down to 200' DH. The 1.5nm spacing is possible because the ILS 28L glideslope was tweaked down a bit to 2.85 degrees a few years ago, providing additional vertical separation from staggered aircraft on the right.