Three terminals at San Diego International Airport (N. Harbor Dr., San Diego, www.san.org [1]) provide easy access to Southern California. (They somehow managed to squeeze the runways in right downtown by the ocean, making it incredibly convenient for visitors to the seaside city.) Long- and short-term parking is available by the hour or day.
The airport is serviced daily by Amtrak (800/872-7245, www.amtrak.com [2]) and by Coaster (www.gonctd.com [3], 800/262-7837, Mon.–Sat., $4) trains via the Santa Fe Deport train station downtown.
The Flyer Route No. 992 metro bus (http://transit.511sd.com [4], 5 a.m.–12:50 a.m., $2.25) stops downtown and connects with the San Diego Trolley, Coaster, and Amtrak. Note that the Trolley does not connect directly to the airport.
Links:
[1] http://www.san.org
[2] http://www.amtrak.com
[3] http://www.gonctd.com
[4] http://transit.511sd.com