This is going to be the eclipse of the century for the USA. To make the most of it, you need to be on the path of totality (see map) to see a total eclipse. If you stay in San Francisco, you will only see a partial eclipse. You need to make arrangements now if you need somewhere to stay.
The gray band indicates the path of totality. Inside it, you will see a total eclipse, and will be able to see the Sun's corona in all its glory. If you are outside the path of totality, you will only see a partial eclipse (and no corona). The closer you are to the blue centerline, the longer totality will last. The black dot near Nashville indicates the location where totality will last the longest (2 minutes and 40 seconds).
During totality (but only totality), it is safe to observe the Sun's corona with the naked eye. At all other times, you will need to use a protective (solar) filter if you want to look at the Sun directly, or project an image of the Sun onto a screen.