From Davis Amtrak train to Santa Clara Caltrain then Caltrain to California Ave Caltrain. 3 h 14 min $55. From Davis drive to Palo Alto. 1 h 50 min $12. From UC Davis Memorial Union bus to Sacramento airport, fly to San Francisco airport, BART to Millbrae Caltrain, then Caltrain to Palo Alto. 4 h 13 min $108.
Amtrak operates a train from Davis to Palo Alto every 4 hours. Tickets cost $30 - $75 and the journey takes 2 h 34 min. Caltrain also services this route every 30 minutes. Alternatively, United Airlines flies from Davis to Palo Alto 5 times a day.