Look at the Mission/Dolores area and Market/Castro... There are a number of new units hitting the market in both areas and they are definitely "safe". Being a big city its always important to be aware of your surroundings and the crime reports maps will just make you think everywhere but the most far flung or mansion districts are the safest. The Mission is full of young professionals as is SOMA and some of the more homogenous neighborhoods like Russian Hill, Cow Hollow, The Marina and Lower Pacific Heights. NOPA/Alamo Square is a great up and coming neighborhood that is also very centrally located and easy to get just about anywhere in the city with ease.