Well, I can talk about Edinburgh and San Francisco and this is a LONG post. I think that the question about resources have been answered for SF but I do not know about resources in Edinburgh.
I will add my
about SF first. I don't think that there is that much crime there. What you may find is more homeless persons than some other cities because of the climate.
Housing is expensive in the city. Your parents may want to think about a suburb. I would look at the East Bay, where Blast-Off-Girl, Meowers and I live. With the housing market and foreclosures being what they are, you can get some bargains. If your parents are interested in the East Bay, be sure that they live near a BART (Bay Area Rapid Transit) line.
Like Sarahp said, the Bay Area has many micro climates. SF has the most temperate weather, but it is very foggy in the summer and will be cold. General rule of thumb is that for every mile east you go from SF you can add a degree. So, in the summer, it can be 65F in SF and about 95F where I live which is 27 miles from downtown SF.
There are many diverse neighborhoods in SF. I wouldn't live in Hunters Point. The Castro Valley is home to many gays and is a nice place to live. Speaking of earthquakes, I wouldn't live in the Marina district because it is filled in land which liquifies during major quakes. You are more likely to be hit by lightning than to live through a major earthquake.
You can drive to so many things here. You can drive to the Sierras for snow, Reno and rafting in the summer. You can see the coastal redwoods just north of SF in Muir woods. You can go to see the Sequoia redwoods in Yosemite which in itself is one of the most beautiful places in the world. Monterey is close and LA is within a days drive but it is another world.
Just kidding for the LA persons.
On to Edinburgh. My daughter and I have been there twice and are so in love with it! Everyone is so friendly. There is so much history there. London is very close. I even like haggis. There is a small town air there even though it is the major city in Scotland. It is hilly like SF and some of the views are spectacular and the pubs are great.
We love the Fringe Festival in August. You can see plays for cheap and they run 23 hours a day. During the festival, Prince Charles and Camilla were there to see the military Tattoo (another annual famous event). They went from the Tattoo to the royal residence at Holyrood in a horse-drawn carriage covered in gold. Think Cinderella only 24 karat.
The food is not as good as it is in SF but then again, not many cities have cuisine like SF. You can drive to, take a train, boat, or plane to many places in Europe.
I cannot tell you about the neighborhoods. I can tell you that the first time we were there we stayed at a lovely B&B. They were full the second time we went but suggested another B&B around the corner. Colin and Trina asked us for breakfast, lunch and dinner while we were there. We still send cards to each other.
To sum up, here are my favorite cities where I have lived or visited:
Sydney (sorry, Sarah)
South Africa is not on my radar.