Quite a few things which made me feel at home in SFO is every few miles you see a Indian restuarant, and the weather is so plesant and good as Ooty and Kodai. Ofcourse I also had my sis there and hence never felt like I was at a new place.
One nice thing here is that, you can commute to all places so easily. So many buses, tram, local trains etc. Infact this is one place where you can fo the complete site seeing all by yourself without a car.
Sometime people say you can see all places in SFO in one day, but then I suggest people spend 2 days in SFO. Only then you can cover all the places at leisure.
In SFO, you can take a one day pass / 3 day pass which will allow you to travel in all SFO buses, muni, trains for 3 days indefinite times. Its the cheapest and best way to commute inside the city. When you pick the pass, you also get a booklet with map giving the details of the cable car routes and stops, muni routes and stops. You just have to decide the places you need to visit and start off.
Infact when you use the muni, you get to see a lot of the city and you might as well end up learning the routes in SFO. When you take the cable car, you can cover Union Square, Nob Hill, China Town, Lombard Street and final destination will be reaching the beach side. Before the final destination you can take a route to reach Coit Tower where you can have a wonderful view of the city. You will also get to see Grace Cathedral on the way.
There starting from beach street , can walk to Ghiradelli Square and museum near by. Then take a longer walk and reach Fisherman warf, check out the submarine there and take the cruise. The ferry cruise gives u various options, either to golden gate bridge and around alcatrez, one around sausalito, one to angel island. It is not possible to find a tour to all places. So its for you to decide which one interests you. Apart from this, you also have a complete Alcatrez tour which will take you to the island , drop you there, you can go around and visit the place and get back after few hrs in another ferry. Regular ferry will only take 1 hr but Alcatrez will take 3 hrs. So based on the time available, you can choose. Remember its very hard to find ferry to Alcatrez, its always needed to book online in advance by a day or so, else you wont find it.
If you continue walking thru, you will cross many more of those ferry tours, you also have tour where it includes a visit to aquarium at Pier 39. As you walk thru the coast you might even end up crossing the ferry building and reaching the market street. But thats indeed a very hard walk, so once you go thru the ferry, you can take a muni and see thru the places from the bus.
I dont know if I have missed any other interesting spot in Market Street.
A little away from this place, you can go to Golden Gate Park, I wonder if i had seen a park as big as this before. Its impossible to walk thru completly. You also have a Tea garden here and a museum, and the tower view of the city near the museum is again amazing and worth a watch. Moving further from Golden Gate Park, you can get to Palace of Fine Arts - wonderful palace, science museum. A little further you will reach the all time special Golden Gate Bridge :)
You have one more special place worth a visit here which is the Twin Peaks. I am not sure on reaching this place by bus as I went in car. This gives one of the best view of the city.
I might have repeated in so many places its beach, coastal view and tower view. But trust me its worth in all ways. Its different and great to watch from each of these places. Some places might be special when you just see in pics, but this place is special and worth a real watch than jus seeing in pics.