@Manc in London here’s an abbreviated perspective of something I sent
@Bill Walker before he came out:
Here's a map by neighbo(u)rhood:
All 70-odd named neighborhoods in the city of San Francisco, as well as the 10 Realtor Districts
www.bayareamarketreports.com
The one area to avoid is the Tenderloin, and the areas South of Market (or SOMA) that abut it. Those areas have been bad for decades. The neighborhoods south of the 280 freeway can also be dicey but you'd have no reason to go down there. For the most part, everywhere else is safe and comfortable though you'll likely encounter the occasional homeless person no matter where.
May and September are usually the best months to visit -- late spring and early fall so it's warm and before/after the fog really starts blowing in from the ocean (which happens in summer). That said, don't underestimate how cold it can get. The air is very, very damp typically. Dress for Manchester any time of year. Wear layers. It can be 10C in San Francisco proper and 30C ten miles north in the summer. We call them microclimates. If I had a dollar for every shivering tourist I saw in t-shirts and shorts on the Golden Gate Bridge I'd be a billionaire.
I am sure you'll do all the traditional visitor stuff -- Fisherman's Wharf, North Beach, the windy part of Lombard, the Haight-Asbury (Hippietown USA), the Painted Ladies, the GG Bridge, cable car, Alcatraz, etc. but one place I hope you do not miss which a lot of visitors do is Golden Gate Park.
https://www.cs.csustan.edu/~john/Pix/golden-gate-park-map.pdf
Around the Concourse is the DeYoung (a great art museum), the California Academy of Sciences (great museum with a fabulous aquarium, earthquake exhibits, a planetarium, and lots of other things) and the Japanese Tea Garden which should be in all its glory in spring or fall. Plus just walking to the many lakes or going to far end to the buffalo paddocks or the beach chalet fields (where I used to play footy as a teenager) where the ocean meets the park is fun.
Also the Presidio (and old military base turned into a national park) is a great place to walk around.
If you have time to go to Muir Woods in Marin County, do it -- its where the redwoods are.
You need to make reservations and take a shuttle these days but they are spectacular. Also taking a ferry over to Sausalito or Tiburon (where I lived for 30 years) can be fun.
I’ll address some more stuff later on.