The closest airport is Sacramento (SMF) (20 minutes by taxi).

Your best option to fly into Sacramento from the West Coast is Southwest Airlines. You get very cheap fares by purchasing the ticket 14 days before departure. Here's the flight schedule and reservation page. 

A prearranged taxi ride (Dan's Cab at $38 is the cheapest at this moment in time) is $14 more than the shuttle bus, but more convenient.

There is a bus service from Sacramento Airport to Davis (Yolo Bus 42B) and from Davis to Sacramento Airport (Yolo Bus 42A). Details can be found here . Roughly the bus visits the airport in both directions at about 20 past the hour. Detailed schedules are 42A and 42B . It can be picked up at either terminal A or terminal B. Cost is $1.50. You will want to exit the bus (or get on the bus when returning to the airport) at UC Davis Memorial Union. From there it is a 5 to 10 minutes walk to downtown hotels (easterly direction) or to the Physics Department (straight south, starting by going through the Memorial Union).

To get to the Physics building, the UC Davis Conference Center, or the Alumni & Visitors Center: Take I-80 to the UC Davis Exit. Follow Old Davis Road to a large parking structure on your right. Park here.

The Physics building is located on the South-East portion of the UC Davis campus, North of the Mondavi Center. The Alumni & Visitors Center and the Conference Center are just north and east of the parking structure.

There is a Visitor parking lot is located near the University Club at the end of A Street. Parking is $6.

A parking structure and parking lot is located south-west of the Alumni & Visitors Center building. Parking is $6.