Sorry for the delay, I did get a chance to review your situation and location this morning.
Sacramento is much more difficult, so let's focus on San Francisco.
First off, look for a line of sight that allows the signals to pass by, not through, the trees immediately across the street. The UHF signals, in particular, will be weak after traveling over the mountains and tree foliage is likely to make them unusable by any antenna, no matter what. You can use the online/interactive maps feature to investigate potential line of sight issues. Switch to the satellite view and turn on the lines to transmitters, then move the balloon around on your virtual rooftop and observe carefully where the green lines fall on the image as compared to your actual view from your rooftop.
If you want to try one of our antennas that's easily available at a local retail store, I'd suggest the ClearStream 4V, available exclusively at Best Buy stores. The math says it ought to work, practical experience says it may if you are patient in finding a good spot. You'll probably need a taller/longer/different mast than the compact 20" one that comes in the box. Do not drill any holes in your roof until you have satisfactorily proven reception.
If you have a Fry's nearby, pick up an RCA preamplifier, it's the best you're going to do in any retail store that I know of. My first choice would be our Juice, but you would have to order it.
Cheers!
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