San Francisco International Airport or Oakland International Airport are both close to the city of San Francisco. You will probably find more options into SFO but it could be less expensive coming into OAK depending on where you're coming from.
Uber / Lyft is the easiest and will range from $25-$40 and should take you 20 minutes except for rush hour which can be 1 hour. BART (subway) goes directly from the airport to multiple locations in SF. If you are traveling during rush hour you may want to consider this option. It’s $8 per person and will take you 40 min depending on where you get off. If you're staying at Park Central Hotel in our room block, you would get off at Montgomery Station and from there it would be about a 10 min walk (.03 miles).
A lyft or uber ride to San Francisco from the airport should be around $30 and the subway (BART) will get you to the city for $8. Once you're in the city you really don't need a car as you can get most places through cabs, rideshare, and public transportation. However, if you do decide to rent a car keep in mind that parking is very limited and often expensive ($50 per night at hotels and $25-$40 at parking garages).