Palo Alto Airport (PAO) is a small, city-owned general-aviation field on the edge of San Francisco Bay in the heart of Silicon Valley, and it is worth saying plainly that this is not an airport with commercial terminals, arrivals halls or on-site rental car desks; it serves private and business aircraft rather than scheduled passenger flights. Travelers using PAO for business in Palo Alto, Menlo Park or Mountain View typically arrange a rental car through a local delivery service that meets the aircraft on the ramp, or they pick up nearby at San Francisco International Airport (SFO) or San Jose Mineta International Airport (SJC), both a manageable drive away with full commercial rental facilities and the usual lineup of major international brands.
SFO sits roughly thirty to forty-five minutes north of Palo Alto depending on Bay Area traffic, while SJC is a similar distance to the south, and either makes a practical rental pickup point for visitors flying commercially into the region before continuing to Palo Alto by road. Once you have a car, Silicon Valley's core - Stanford University, downtown Palo Alto and the office campuses spread along Highway 101 and El Camino Real - is compact enough that most destinations are within twenty or thirty minutes of each other on a normal traffic day.
Driving is on the right throughout the United States, and this part of the Bay Area has no tolls on its local roads, though the region's bridges, including the Dumbarton and San Mateo crossings nearby, do charge tolls collected electronically. Traffic on Highway 101 and El Camino Real is heaviest during weekday commute windows, often stretching well beyond the traditional rush hour, so building in extra time for any drive through the Peninsula is a sensible habit for visitors renting a car near this quiet general-aviation field.