Stanford University is conveniently located near three regional airports. One of them is SFO, located 30-45 minutes from campus. There are public transportation options to campus if needed: https://transportation.stanford.edu/maps-resources-access/sustainable-transportation/transportation-airports.
Another option is SJC. This airport is 20-30 minutes from Stanford. It also has public transportation options: https://transportation.stanford.edu/maps-resources-access/sustainable-transportation/transportation-airports.
Lastly, you can fly into OAK. This airport is 40-50 minutes from Stanford. Public transportation: https://transportation.stanford.edu/maps-resources-access/sustainable-transportation/transportation-airports.