I think a hop on hop off bus tour is a must do in any city as you can see all the sights from the comfort of the open top bus, listen to the commentary and then hop off and explore further where sparks your interest.
We bought the bus tour and Alcatraz ticket combination, we got to the office as it opened at 8am, hopped on the first bus and took in the sights, the bus goes over the Golden Gate Bridge so you get to see this iconic bridge from all angles. It stops just after so you can hop off and have a stroll take some photos and in 15 mins the next bus will be along to pick you up.
We booked our Alcatraz visit for the last boat over, so it was quieter later in the day and not as hot. Make sure you leave time though to swap your vouchers at the Pier 33 ticket office.
Some of the buses are wheelchair accessible but you may have to wait slightly longer if you require this bus as not all of them are adapted. The boats and Alcatraz is all wheelchair accessible.
The staff were friendly and helpful and very knowledgeable about the city.